diff --git a/pydantic_mongo/abstract_repository.py b/pydantic_mongo/abstract_repository.py
index 00f5e46..4466f7e 100644
--- a/pydantic_mongo/abstract_repository.py
+++ b/pydantic_mongo/abstract_repository.py
@@ -10,6 +10,7 @@
     TypeVar,
     Union,
     Mapping,
+    List,
 )
 
 import asyncio
@@ -37,7 +38,7 @@
 T = TypeVar("T", bound=BaseModel)
 OutputT = TypeVar("OutputT", bound=BaseModel)
 
-Sort = Sequence[Tuple[str, int]]
+Sort = Union[str, Sequence[Tuple[str, int]], Tuple[str, int]]
 
 
 class AbstractRepository(Generic[T]):
@@ -98,14 +99,19 @@ def __map_id(self, data: dict) -> dict:
             query["_id"] = query.pop("id")
         return query
 
-    def __map_sort(self, sort: Sort) -> Optional[Sort]:
+    def __map_sort(self, sort: Sort) -> str | list[tuple] | list[tuple[str | Any, Any]]:
         result = []
-        for item in sort:
-            key = item[0]
-            ordering = item[1]
-            if key == "id":
-                key = "_id"
-            result.append((key, ordering))
+        if isinstance(sort, str):
+            return sort
+        elif isinstance(sort, tuple):
+            return [sort]
+        elif isinstance(sort, list):
+            for item in sort:
+                key = item[0]
+                ordering = item[1]
+                if key == "id":
+                    key = "_id"
+                result.append((key, ordering))
         return result
 
     def to_model_custom(self, output_type: Type[OutputT], data: Union[dict, Mapping[str, Any]]) -> OutputT:
@@ -422,14 +428,19 @@ def __map_id(self, data: dict) -> dict:
             query["_id"] = query.pop("id")
         return query
 
-    def __map_sort(self, sort: Sort) -> Optional[Sort]:
+    def __map_sort(self, sort: Sort) -> str | list[tuple] | list[tuple[str | Any, Any]]:
         result = []
-        for item in sort:
-            key = item[0]
-            ordering = item[1]
-            if key == "id":
-                key = "_id"
-            result.append((key, ordering))
+        if isinstance(sort, str):
+            return sort
+        elif isinstance(sort, tuple):
+            return [sort]
+        elif isinstance(sort, list):
+            for item in sort:
+                key = item[0]
+                ordering = item[1]
+                if key == "id":
+                    key = "_id"
+                result.append((key, ordering))
         return result
 
     def to_model_custom(self, output_type: Type[OutputT], data: Union[dict, Mapping[str, Any]]) -> OutputT: