diff --git a/src/sap_cloud_sdk/core/telemetry/auto_instrument.py b/src/sap_cloud_sdk/core/telemetry/auto_instrument.py
index fef7842e..1b4c0ebe 100644
--- a/src/sap_cloud_sdk/core/telemetry/auto_instrument.py
+++ b/src/sap_cloud_sdk/core/telemetry/auto_instrument.py
@@ -169,8 +169,15 @@ def _merge_resource_attrs_into_active_provider_if_wrapper_installed(
     if "telemetry.auto.version" not in existing_attrs:
         return
 
-    provider._resource = provider.resource.merge(Resource.create(sap_attrs))
+    merged = provider.resource.merge(Resource.create(sap_attrs))
+
+    with provider._tracers_lock:
+        provider._resource = merged
+        for tracer in provider._tracers.values():
+            tracer.resource = merged
+
     logger.info(
         "Merged sap-cloud-sdk resource attrs onto wrapper-installed "
-        "TracerProvider (marker: telemetry.auto.version)"
+        "TracerProvider and %d cached Tracer(s) (marker: telemetry.auto.version)",
+        len(provider._tracers),
     )
diff --git a/tests/core/unit/telemetry/test_auto_instrument.py b/tests/core/unit/telemetry/test_auto_instrument.py
index 98ed6328..220feded 100644
--- a/tests/core/unit/telemetry/test_auto_instrument.py
+++ b/tests/core/unit/telemetry/test_auto_instrument.py
@@ -330,6 +330,38 @@ def test_auto_instrument_merge_overrides_colliding_service_name(self, mock_trace
 
             assert wrapper_provider.resource.attributes['service.name'] == 'cloud-sdk-app'
 
+    def test_auto_instrument_back_patches_cached_tracers(self, mock_traceloop_components):
+        """Tracer objects cached in provider._tracers before auto_instrument() is
+        called must have their resource updated to the merged resource."""
+        mock_traceloop_components['get_app_name'].return_value = 'cloud-sdk-app'
+        sap_attrs = {
+            'service.name': 'cloud-sdk-app',
+            'sap.cloud_sdk.name': 'SAP Cloud SDK for Python',
+            'sap.cloud_sdk.language': 'python',
+        }
+        mock_traceloop_components['create_resource'].return_value = sap_attrs
+
+        wrapper_provider = SDKTracerProvider(
+            resource=Resource.create({
+                'telemetry.auto.version': '0.62b1',
+                'service.name': 'operator-supplied-name',
+            })
+        )
+        mock_traceloop_components['get_tracer_provider'].return_value = wrapper_provider
+
+        pre_merge_tracer_a = wrapper_provider.get_tracer("opentelemetry.instrumentation.requests")
+        pre_merge_tracer_b = wrapper_provider.get_tracer("opentelemetry.instrumentation.langchain")
+        pre_merge_resource = pre_merge_tracer_a.resource
+
+        with patch.dict('os.environ', {'OTEL_EXPORTER_OTLP_ENDPOINT': 'http://localhost:4317'}, clear=True):
+            auto_instrument()
+
+        merged_resource = wrapper_provider.resource
+        assert merged_resource.attributes['sap.cloud_sdk.name'] == 'SAP Cloud SDK for Python'
+        assert pre_merge_tracer_a.resource is merged_resource
+        assert pre_merge_tracer_b.resource is merged_resource
+        assert pre_merge_tracer_a.resource is not pre_merge_resource
+
 
 class TestAutoInstrumentMiddlewares:
     """Tests for the middlewares parameter of auto_instrument."""