diff --git a/fastchat/llm_judge/common.py b/fastchat/llm_judge/common.py
index ad1180034..064056a5c 100644
--- a/fastchat/llm_judge/common.py
+++ b/fastchat/llm_judge/common.py
@@ -11,7 +11,8 @@
 import time
 from typing import Optional
 
-import openai
+from openai import OpenAI, OpenAIError
+
 import anthropic
 
 from fastchat.model.model_adapter import get_conversation_template
@@ -398,20 +399,21 @@ def play_a_match_pair(match: MatchPair, output_file: str):
 
 
 def chat_compeletion_openai(model, conv, temperature, max_tokens):
+    client = OpenAI()
     output = API_ERROR_OUTPUT
     for _ in range(API_MAX_RETRY):
         try:
             messages = conv.to_openai_api_messages()
-            response = openai.ChatCompletion.create(
+            response = client.chat.completions.create(
                 model=model,
                 messages=messages,
                 n=1,
                 temperature=temperature,
-                max_tokens=max_tokens,
+                max_tokens=max_tokens
             )
-            output = response["choices"][0]["message"]["content"]
+            output = response.choices[0].message.content
             break
-        except openai.error.OpenAIError as e:
+        except OpenAIError as e:
             print(type(e), e)
             time.sleep(API_RETRY_SLEEP)
 
diff --git a/fastchat/llm_judge/gen_api_answer.py b/fastchat/llm_judge/gen_api_answer.py
index 151acd2d4..6382527b3 100644
--- a/fastchat/llm_judge/gen_api_answer.py
+++ b/fastchat/llm_judge/gen_api_answer.py
@@ -114,7 +114,7 @@ def get_answer(
     args = parser.parse_args()
 
     if args.openai_api_base is not None:
-        openai.api_base = args.openai_api_base
+        raise ValueError("The 'openai.api_base' option is not available in openai>=1.0, pass it when you instantiate the client, e.g. 'OpenAI(base_url=args.openai_api_base)")
 
     question_file = f"data/{args.bench_name}/question.jsonl"
     questions = load_questions(question_file, args.question_begin, args.question_end)