diff --git a/fastapi/_compat.py b/fastapi/_compat.py
index 227ad837d..aac167b02 100644
--- a/fastapi/_compat.py
+++ b/fastapi/_compat.py
@@ -93,7 +93,13 @@ if PYDANTIC_V2:
 
         @property
         def alias(self) -> str:
-            a = self.field_info.alias
+            match self.mode:
+                case "validation" if self.field_info.validation_alias is not None:
+                    a = self.field_info.validation_alias
+                case "serialization" if self.field_info.serialization_alias is not None:
+                    a = self.field_info.serialization_alias
+                case _:
+                    a = self.field_info.alias
             return a if a is not None else self.name
 
         @property