diff --git a/sqlglot/dialects/bigquery.py b/sqlglot/dialects/bigquery.py
index 68d82c696..bf718d3b5 100644
--- a/sqlglot/dialects/bigquery.py
+++ b/sqlglot/dialects/bigquery.py
@@ -323,6 +323,7 @@ class Tokenizer(tokens.Tokenizer):
             "BEGIN TRANSACTION": TokenType.BEGIN,
             "BYTES": TokenType.BINARY,
             "CURRENT_DATETIME": TokenType.CURRENT_DATETIME,
+            "DATETIME": TokenType.TIMESTAMP,
             "DECLARE": TokenType.COMMAND,
             "ELSEIF": TokenType.COMMAND,
             "EXCEPTION": TokenType.COMMAND,
diff --git a/tests/dialects/test_bigquery.py b/tests/dialects/test_bigquery.py
index 277caa488..1cad1a7df 100644
--- a/tests/dialects/test_bigquery.py
+++ b/tests/dialects/test_bigquery.py
@@ -1098,6 +1098,13 @@ def test_bigquery(self):
                 "postgres": "SELECT x % 10",
             },
         )
+        self.validate_all(
+            "SELECT CAST(x AS DATETIME)",
+            write={
+                "": "SELECT CAST(x AS TIMESTAMP)",
+                "bigquery": "SELECT CAST(x AS DATETIME)",
+            },
+        )
 
     def test_errors(self):
         with self.assertRaises(TokenError):
diff --git a/tests/dialects/test_duckdb.py b/tests/dialects/test_duckdb.py
index 55c40ccf0..2cfb6b4cf 100644
--- a/tests/dialects/test_duckdb.py
+++ b/tests/dialects/test_duckdb.py
@@ -755,7 +755,7 @@ def test_time(self):
             "SELECT MAKE_DATE(2016, 12, 25)", read={"bigquery": "SELECT DATE(2016, 12, 25)"}
         )
         self.validate_all(
-            "SELECT CAST(CAST('2016-12-25 23:59:59' AS DATETIME) AS DATE)",
+            "SELECT CAST(CAST('2016-12-25 23:59:59' AS TIMESTAMP) AS DATE)",
             read={"bigquery": "SELECT DATE(DATETIME '2016-12-25 23:59:59')"},
         )
         self.validate_all(