diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -670,6 +670,8 @@
 - Correcly diagnose jumps into statement expressions.
   This ensures the behavior of Clang is consistent with GCC.
   (`#63682 <https://github.com/llvm/llvm-project/issues/63682>`_)
+- Fix crash on nested templated class with template function call.
+  (`#61159 <https://github.com/llvm/llvm-project/issues/61159>_`)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -258,6 +258,11 @@
                                        /*Final=*/false);
   }
 
+  if (const MemberSpecializationInfo *MSInfo =
+          Rec->getMemberSpecializationInfo())
+    if (MSInfo->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
+      return Response::Done();
+
   bool IsFriend = Rec->getFriendObjectKind() ||
                   (Rec->getDescribedClassTemplate() &&
                    Rec->getDescribedClassTemplate()->getFriendObjectKind());
diff --git a/clang/test/SemaTemplate/gh61159.cpp b/clang/test/SemaTemplate/gh61159.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaTemplate/gh61159.cpp
@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++20 %s
+// expected-no-diagnostics
+
+namespace GH61159 {
+template <typename T> struct X {
+  struct I;
+};
+
+template <> struct X<int>::I {
+  template <int ct> constexpr int f() { return ct; };
+
+  int data = 3;
+};
+
+template <typename T> struct X<T>::I {
+  template <T ct> constexpr T f() { return ct + 1; };
+  T data = 7;
+};
+
+static_assert(X<int>::I{}.f<17>() == 17);
+static_assert(X<int>::I{}.data == 3);
+static_assert(X<short>::I{}.data == 7);
+static_assert(X<short>::I{}.f<18>() == 19);
+
+template <typename T> struct Y {
+  struct I;
+};
+
+template <> struct Y<int> {
+  struct I {
+    template <int ct> constexpr int f() { return ct; };
+    int data = 3;
+  };
+};
+
+static_assert(Y<int>::I{}.f<17>() == 17);
+static_assert(Y<int>::I{}.data == 3);
+
+} // namespace GH61159