diff --git a/tests/test_litellm/litellm_core_utils/test_get_litellm_params.py b/tests/test_litellm/litellm_core_utils/test_get_litellm_params.py
new file mode 100644
index 00000000000..dbcb048c250
--- /dev/null
+++ b/tests/test_litellm/litellm_core_utils/test_get_litellm_params.py
@@ -0,0 +1,127 @@
+"""
+Tests for get_litellm_params and related helpers.
+
+Ensures backward compatibility after sparse kwargs extraction optimization.
+"""
+
+import pytest
+
+from litellm.litellm_core_utils.get_litellm_params import (
+    _OPTIONAL_KWARGS_KEYS,
+    _get_base_model_from_litellm_call_metadata,
+    get_litellm_params,
+)
+
+
+class TestGetBaseModelFromLitellmCallMetadata:
+    def test_none_metadata_returns_none(self):
+        assert _get_base_model_from_litellm_call_metadata(None) is None
+
+    def test_empty_metadata_returns_none(self):
+        assert _get_base_model_from_litellm_call_metadata({}) is None
+
+    def test_missing_model_info_returns_none(self):
+        assert _get_base_model_from_litellm_call_metadata({"foo": "bar"}) is None
+
+    def test_model_info_none_returns_none(self):
+        assert _get_base_model_from_litellm_call_metadata({"model_info": None}) is None
+
+    def test_model_info_empty_dict_returns_none(self):
+        assert _get_base_model_from_litellm_call_metadata({"model_info": {}}) is None
+
+    def test_returns_base_model(self):
+        result = _get_base_model_from_litellm_call_metadata(
+            {"model_info": {"base_model": "gpt-4"}}
+        )
+        assert result == "gpt-4"
+
+
+class TestGetLitellmParamsKwargsExtraction:
+    """Verify that optional kwargs are correctly extracted via sparse extraction."""
+
+    def test_no_kwargs_omits_optional_keys(self):
+        """When no kwargs passed, optional keys should not be in result."""
+        result = get_litellm_params(api_key="test-key")
+        for key in _OPTIONAL_KWARGS_KEYS:
+            assert key not in result
+
+    def test_present_kwargs_are_extracted(self):
+        result = get_litellm_params(
+            aws_region_name="us-east-1",
+            timeout=30,
+            rpm=100,
+        )
+        assert result["aws_region_name"] == "us-east-1"
+        assert result["timeout"] == 30
+        assert result["rpm"] == 100
+
+    def test_subset_of_kwargs_only_includes_provided(self):
+        """Only provided kwargs appear, others remain absent."""
+        result = get_litellm_params(azure_ad_token="token123")
+        assert result["azure_ad_token"] == "token123"
+        assert "aws_region_name" not in result
+        assert "timeout" not in result
+
+    def test_unknown_kwargs_are_ignored(self):
+        result = get_litellm_params(some_random_kwarg="value")
+        assert "some_random_kwarg" not in result
+
+    def test_all_optional_kwargs_extractable(self):
+        """Every key in _OPTIONAL_KWARGS_KEYS can be extracted."""
+        kwargs = {key: f"val_{key}" for key in _OPTIONAL_KWARGS_KEYS}
+        result = get_litellm_params(**kwargs)
+        for key in _OPTIONAL_KWARGS_KEYS:
+            assert result[key] == f"val_{key}"
+
+
+class TestGetLitellmParamsBaseModel:
+    """Verify base_model resolution precedence."""
+
+    def test_explicit_base_model_takes_precedence(self):
+        result = get_litellm_params(
+            base_model="explicit",
+            metadata={"model_info": {"base_model": "from-metadata"}},
+        )
+        assert result["base_model"] == "explicit"
+
+    def test_falls_back_to_metadata(self):
+        result = get_litellm_params(
+            metadata={"model_info": {"base_model": "from-metadata"}}
+        )
+        assert result["base_model"] == "from-metadata"
+
+    def test_none_when_no_source(self):
+        result = get_litellm_params()
+        assert result["base_model"] is None
+
+
+class TestGetLitellmParamsExplicitFields:
+    """Verify explicit parameters are always present in the result."""
+
+    def test_explicit_params_always_present(self):
+        result = get_litellm_params()
+        # Spot-check a few explicit keys that should always be in the dict
+        expected_keys = [
+            "acompletion",
+            "api_key",
+            "force_timeout",
+            "verbose",
+            "custom_llm_provider",
+            "api_base",
+            "metadata",
+            "model_info",
+            "max_retries",
+            "ssl_verify",
+            "api_version",
+        ]
+        for key in expected_keys:
+            assert key in result
+
+    def test_no_log_from_kwargs(self):
+        """no-log can come via **kwargs as well as the explicit param."""
+        result = get_litellm_params(**{"no-log": True})
+        assert result["no-log"] is True
+
+    def test_no_log_from_explicit_param(self):
+        result = get_litellm_params(no_log=True)
+        assert result["no-log"] is True