diff --git a/NEWS.md b/NEWS.md
index 92ef6b4c4a..2b5ebe3015 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -18,6 +18,8 @@
 
 2. `DT[i]` could segfault when `i` is a zero-column `data.table`, [#4060](https://github.com/Rdatatable/data.table/issues/4060). Thanks @shrektan for reporting and fixing.
 
+3. Dispatch of `first` and `last` functions now properly works again for `xts` objects, [#4053](https://github.com/Rdatatable/data.table/issues/4053). Thanks to @ethanbsmith for reporting.
+
 ## NOTES
 
 1. `as.IDate`, `as.ITime`, `second`, `minute`, and `hour` now recognize UTC equivalents for speed: GMT, GMT-0, GMT+0, GMT0, Etc/GMT, and Etc/UTC, [#4116](https://github.com/Rdatatable/data.table/issues/4116).
diff --git a/R/last.R b/R/last.R
index 052f8e8277..8b26b92850 100644
--- a/R/last.R
+++ b/R/last.R
@@ -1,41 +1,84 @@
-
 # data.table defined last(x) with no arguments, just for last. If you need the last 10 then use tail(x,10).
-# This last is implemented this way for compatibility with xts::last which is S3 generic taking 'n' and 'keep' arguments
-# We'd like last() on vectors to be fast, so that's a direct x[NROW(x)] as it was in data.table, otherwise use xts's.
-# If xts is loaded higher than data.table, xts::last will work but slower.
+# for xts class objects it will dispatch to xts::last
+# reworked to avoid loading xts namespace (#3857) then again to fix dispatching of xts class (#4053)
 last = function(x, n=1L, ...) {
-  if (nargs()==1L) {
-    if (is.vector(x) || is.atomic(x)) {
-      if (!length(x)) x else x[[length(x)]]
-    } else if (is.data.frame(x)) {
-      x[NROW(x),]
+  verbose = isTRUE(getOption("datatable.verbose", FALSE))
+  if (!inherits(x, "xts")) {
+    if (nargs()>1L) {
+      if ("package:xts" %chin% search()) {
+        if (verbose)
+          cat("last: using xts::last: !is.xts(x) & nargs>1 & 'package:xts'%in%search()\n")
+        xts::last(x, n=n, ...)
+      } else {
+        # nocov start
+        if (verbose)
+          cat("last: using utils::tail: !is.xts(x) & nargs>1 & !'package:xts'%in%search()\n")
+        utils::tail(x, n=n, ...)
+        # nocov end
+      }
+    } else {
+      dx = dim(x)
+      if (is.null(dx)) {
+        if (verbose)
+          cat("last: using 'x[[length(x)]]': !is.xts(x) & !nargs>1 & is.null(dim(x))\n")
+        lx = length(x)
+        if (!lx) x else x[[lx]]
+      } else if (is.data.frame(x)) {
+        if (verbose)
+          cat("last: using 'x[nrow(x),]': !is.xts(x) & !nargs>1 & is.data.frame(x)\n")
+        x[dx[1L], , drop=FALSE]
+      } else {
+        if (verbose)
+          cat("last: using utils::tail: !is.xts(x) & !nargs>1 & !is.null(dim(x)) & !is.data.frame(x)\n")
+        utils::tail(x, n=n, ...)
+      }
     }
-  } else if ("package:xts" %chin% search()) {
-    if (!requireNamespace("xts", quietly=TRUE))
-      stop("internal error, package:xts is on search path but could not be loaded via requireNamespace") # nocov
-    if (isTRUE(getOption("datatable.verbose", FALSE)))
-      cat("last: using xts::last\n")
-    xts::last(x, n=n, ...) # UseMethod("last") doesn't find xts's methods, not sure what I did wrong.
   } else {
-    tail(x, n=n, ...) # nocov
+    if (!requireNamespace("xts", quietly=TRUE))
+      stop("'xts' class passed to data.table::last function but 'xts' is not available, you should have 'xts' installed already") # nocov
+    if (verbose)
+      cat("last: using xts::last: is.xts(x)\n")
+    xts::last(x, n=n, ...)
   }
 }
 
-# first(), similar to last(), not sure why this wasn't exported in the first place...
 first = function(x, n=1L, ...) {
-  if (nargs()==1L) {
-    if (is.vector(x) || is.atomic(x)) {
-      if (!length(x)) x else x[[1L]]
-    } else if (is.data.frame(x)) {
-      if (!NROW(x)) x else x[1L,]
+  verbose = isTRUE(getOption("datatable.verbose", FALSE))
+  if (!inherits(x, "xts")) {
+    if (nargs()>1L) {
+      if ("package:xts" %chin% search()) {
+        if (verbose)
+          cat("first: using xts::first: !is.xts(x) & nargs>1 & 'package:xts'%in%search()\n")
+        xts::first(x, n=n, ...)
+      } else {
+        # nocov start
+        if (verbose)
+          cat("first: using utils::head: !is.xts(x) & nargs>1 & !'package:xts'%in%search()\n")
+        utils::head(x, n=n, ...)
+        # nocov end
+      }
+    } else {
+      dx = dim(x)
+      if (is.null(dx)) {
+        if (verbose)
+          cat("first: using 'x[[1L]]': !is.xts(x) & !nargs>1 & is.null(dim(x))\n")
+        lx = length(x)
+        if (!lx) x else x[[1L]]
+      } else if (is.data.frame(x)) {
+        if (verbose)
+          cat("first: using 'x[1L,]': !is.xts(x) & !nargs>1 & is.data.frame(x)\n")
+        if (!dx[1L]) x else x[1L, , drop=FALSE]
+      } else {
+        if (verbose)
+          cat("first: using utils::head: !is.xts(x) & !nargs>1 & !is.null(dim(x)) & !is.data.frame(x)\n")
+        utils::head(x, n=n, ...)
+      }
     }
-  } else if ("package:xts" %chin% search()) {
+  } else {
     if (!requireNamespace("xts", quietly=TRUE))
-      stop("internal error, package:xts is on search path but could not be loaded via requireNamespace") # nocov
-    if (isTRUE(getOption("datatable.verbose", FALSE)))
-      cat("first: using xts::first\n")
+      stop("'xts' class passed to data.table::first function but 'xts' is not available, you should have 'xts' installed already") # nocov
+    if (verbose)
+      cat("first: using xts::first: is.xts(x)\n")
     xts::first(x, n=n, ...)
-  } else {
-    head(x, n=n, ...) # nocov
   }
 }
diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index be9f70da5f..b3130723f6 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -16161,23 +16161,106 @@ test(2107.3, names(DT), c('A','b','c'))
 setnames(DT, -(1:2), toupper)
 test(2107.4, names(DT), c('A','b','C'))
 
-# first and last should no longer load xts namespace, #3857
+# first and last should no longer load xts namespace, #3857, below commented test for interactive validation when xts present but not loaded or attached
+#stopifnot("xts"%in%installed.packages(), !"xts"%in%loadedNamespaces()); library(data.table); x=as.POSIXct("2019-01-01"); last(x); stopifnot(!"xts" %in% loadedNamespaces())
 x = as.POSIXct("2019-09-09")+0:1
 old = options(datatable.verbose=TRUE)
-test(2108.01, last(x), x[length(x)], notOutput="xts")
-test(2108.02, first(x), x[1L], notOutput="xts")
+test(2108.01, last(x), x[length(x)], output="!is.xts(x)")
+test(2108.02, first(x), x[1L], output="!is.xts(x)")
 if (test_xts) {
   xt = xts(1:2, x)
-  test(2108.03, last(xt, 2L), xt, output="last: using xts::last")
-  test(2108.04, first(xt, 2L), xt, output="first: using xts::first")
+  test(2108.03, last(xt, 2L), xt, output="using xts::last: is.xts(x)")
+  test(2108.04, first(xt, 2L), xt, output="using xts::first: is.xts(x)")
   xt = xts(matrix(1:4, 2L, 2L), x)
-  test(2108.05, last(xt, 2L), xt, output="last: using xts::last")
-  test(2108.06, first(xt, 2L), xt, output="first: using xts::first")
+  test(2108.05, last(xt, 2L), xt, output="using xts::last: is.xts(x)")
+  test(2108.06, first(xt, 2L), xt, output="using xts::first: is.xts(x)")
 }
 # first on empty df now match head(df, n=1L), #3858
 df = data.frame(a=integer(), b=integer())
-test(2108.11, first(df), df, notOutput="xts")
-test(2108.12, tail(df), df, notOutput="xts")
+test(2108.11, first(df), df, output="!is.xts(x)")
+test(2108.12, last(df), df, output="!is.xts(x)")
+options(old)
+# xts last-first dispatch fix #4053
+x = 1:3
+y = as.POSIXct(x, origin="1970-01-01")
+df = data.frame(a=1:2, b=3:2)
+dt = as.data.table(df)
+mx = matrix(1:9, 3, 3)
+ar = array(1:27, c(3,3,3))
+xt = structure(
+  c(142.25, 141.229996, 141.330002, 142.860001, 142.050003, 141.399994,
+    140.570007, 140.610001, 140.380005, 141.369995, 141.669998, 140.539993,
+    94807600, 69620600, 76645300, 108.999954, 109.231255, 108.360008),
+  class = c("xts", "zoo"), .indexCLASS = "Date", tclass = "Date", .indexTZ = "UTC", tzone = "UTC",
+  index = structure(c(1167782400, 1167868800, 1167955200), tzone = "UTC", tclass = "Date"),
+  .Dim = c(3L, 6L), .Dimnames = list(NULL, c("SPY.Open", "SPY.High", "SPY.Low", "SPY.Close", "SPY.Volume", "SPY.Adjusted"))
+)
+old = options(datatable.verbose=TRUE)
+if (test_xts) {
+  test(2108.21, last(x, n=2L), 2:3, output="using xts::last: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  test(2108.22, last(y, n=2L), y[2:3], output="using xts::last: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  test(2108.23, last(x, n=1L), 3L, output="using xts::last: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  test(2108.24, last(y, n=1L), y[3L], output="using xts::last: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  xt_last = structure(
+    c(141.330002, 141.399994, 140.380005, 140.539993, 76645300, 108.360008),
+    class = c("xts", "zoo"), .indexCLASS = "Date", tclass = "Date", .indexTZ = "UTC", tzone = "UTC",
+    index = structure(1167955200, tzone = "UTC", tclass = "Date"),
+    .Dim = c(1L, 6L), .Dimnames = list(NULL, c("SPY.Open", "SPY.High", "SPY.Low", "SPY.Close", "SPY.Volume", "SPY.Adjusted"))
+  )
+  xt_last2 = structure(
+    c(141.229996, 141.330002, 142.050003, 141.399994, 140.610001, 140.380005,
+      141.669998, 140.539993, 69620600, 76645300, 109.231255, 108.360008),
+    class = c("xts", "zoo"), .indexCLASS = "Date", tclass = "Date", .indexTZ = "UTC", tzone = "UTC",
+    index = structure(c(1167868800, 1167955200), tzone = "UTC", tclass = "Date"),
+    .Dim = c(2L, 6L), .Dimnames = list(NULL, c("SPY.Open", "SPY.High", "SPY.Low", "SPY.Close", "SPY.Volume", "SPY.Adjusted"))
+  )
+  test(2108.25, last(xt), xt_last, output="using xts::last: is.xts(x)")
+  test(2108.26, last(xt, n=2L), xt_last2, output="using xts::last: is.xts(x)")
+  test(2108.31, first(x, n=2L), 1:2, output="using xts::first: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  test(2108.32, first(y, n=2L), y[1:2], output="using xts::first: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  test(2108.33, first(x, n=1L), 1L, output="using xts::first: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  test(2108.34, first(y, n=1L), y[1L], output="using xts::first: !is.xts(x) & nargs>1 & 'package:xts'%in%search()")
+  xt_first = structure(
+    c(142.25, 142.860001, 140.570007, 141.369995, 94807600, 108.999954),
+    class = c("xts", "zoo"), .indexCLASS = "Date", tclass = "Date", .indexTZ = "UTC", tzone = "UTC",
+    index = structure(1167782400, tzone = "UTC", tclass = "Date"),
+    .Dim = c(1L, 6L), .Dimnames = list(NULL, c("SPY.Open", "SPY.High", "SPY.Low", "SPY.Close", "SPY.Volume", "SPY.Adjusted"))
+  )
+  xt_first2 = structure(
+    c(142.25, 141.229996, 142.860001, 142.050003, 140.570007, 140.610001, 141.369995, 141.669998, 94807600, 69620600, 108.999954, 109.231255),
+    class = c("xts", "zoo"), .indexCLASS = "Date", tclass = "Date", .indexTZ = "UTC", tzone = "UTC",
+    index = structure(c(1167782400, 1167868800), tzone = "UTC", tclass = "Date"),
+    .Dim = c(2L, 6L), .Dimnames = list(NULL, c("SPY.Open", "SPY.High", "SPY.Low", "SPY.Close", "SPY.Volume", "SPY.Adjusted"))
+  )
+  test(2108.35, first(xt), xt_first, output="using xts::first: is.xts(x)")
+  test(2108.36, first(xt, n=2L), xt_first2, output="using xts::first: is.xts(x)")
+} else {
+  test(2108.21, last(x, n=2L), 2:3, output="using utils::tail: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.22, last(y, n=2L), y[2:3], output="using utils::tail: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.23, last(x, n=1L), 3L, output="using utils::tail: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.24, last(y, n=1L), y[3L], output="using utils::tail: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.25, last(xt), error="you should have 'xts' installed already")
+  test(2108.26, last(xt, n=2L), error="you should have 'xts' installed already")
+  test(2108.31, first(x, n=2L), 1:2, output="using utils::head: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.32, first(y, n=2L), y[1:2], output="using utils::head: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.33, first(x, n=1L), 1L, output="using utils::head: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.34, first(y, n=1L), y[1L], output="using utils::head: !is.xts(x) & nargs>1 & !'package:xts'%in%search()")
+  test(2108.35, first(xt), error="you should have 'xts' installed already")
+  test(2108.36, first(xt, n=2L), error="you should have 'xts' installed already")
+}
+test(2108.41, last(x), 3L, output="using 'x[[length(x)]]': !is.xts(x) & !nargs>1 & is.null(dim(x))")
+test(2108.42, last(y), y[3L], output="using 'x[[length(x)]]': !is.xts(x) & !nargs>1 & is.null(dim(x))")
+test(2108.51, first(x), 1L, output="using 'x[[1L]]': !is.xts(x) & !nargs>1 & is.null(dim(x))")
+test(2108.52, first(y), y[1L], output="using 'x[[1L]]': !is.xts(x) & !nargs>1 & is.null(dim(x))")
+test(2108.61, last(df), structure(list(a=2L, b=2L), row.names=2L, class="data.frame"), output="using 'x[nrow(x),]': !is.xts(x) & !nargs>1 & is.data.frame(x)")
+test(2108.62, last(dt), data.table(a=2L, b=2L), output="using 'x[nrow(x),]': !is.xts(x) & !nargs>1 & is.data.frame(x)")
+test(2108.71, first(df), structure(list(a=1L, b=3L), row.names=1L, class="data.frame"), output="using 'x[1L,]': !is.xts(x) & !nargs>1 & is.data.frame(x)")
+test(2108.72, first(dt), data.table(a=1L, b=3L), output="using 'x[1L,]': !is.xts(x) & !nargs>1 & is.data.frame(x)")
+# matrix/array utils::tail behavior is likely to change in future R, Michael is more in the topic
+test(2108.81, last(mx), structure(c(3L, 6L, 9L), .Dim = c(1L, 3L), .Dimnames = list("[3,]", NULL)), output="using utils::tail: !is.xts(x) & !nargs>1 & !is.null(dim(x)) & !is.data.frame(x)")
+test(2108.82, last(ar), 27L, output="using utils::tail: !is.xts(x) & !nargs>1 & !is.null(dim(x)) & !is.data.frame(x)")
+test(2108.91, first(mx), structure(c(1L, 4L, 7L), .Dim = c(1L, 3L)), output="using utils::head: !is.xts(x) & !nargs>1 & !is.null(dim(x)) & !is.data.frame(x)")
+test(2108.92, first(ar), 1L, output="using utils::head: !is.xts(x) & !nargs>1 & !is.null(dim(x)) & !is.data.frame(x)")
 options(old)
 
 # error in autonaming by={...}, #3156