diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala
index 3e76d3c978..12946b11b3 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/rewrite/RedundantBraces.scala
@@ -253,10 +253,17 @@ class RedundantBraces(implicit val ftoks: FormatTokens)
     owner match {
       case t: Term.FunctionTerm if t.tokens.last.is[Token.RightBrace] =>
         if (!okToRemoveFunctionInApplyOrInit(t)) null else removeToken
-      case t: Term.PartialFunction if t.parent.exists { p =>
-            SingleArgInBraces.orBlock(p).exists(_._2 eq t) &&
-            t.pos.start != p.pos.start
-          } => removeToken
+      case t: Term.PartialFunction => t.parent match {
+          case Some(SingleArgInBraces.OrBlock(lft, `t`, _))
+              if lft.left ne ft.right =>
+            val ok = ftoks.findTokenWith(lft, ftoks.prev) { xft =>
+              if (!xft.left.is[Token.LeftBrace]) Some(false)
+              else if (session.isRemovedOnLeft(xft, ok = true)) None
+              else Some(true)
+            }.contains(true)
+            if (ok) removeToken else null
+          case _ => null
+        }
       case t: Term.Block => t.parent match {
           case Some(f: Term.FunctionTerm)
               if okToReplaceFunctionInSingleArgApply(f) => removeToken
diff --git a/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat b/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat
index 35fe9ca762..14dd45356d 100644
--- a/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat
+++ b/scalafmt-tests/shared/src/test/resources/rewrite/RedundantBraces-if.stat
@@ -393,3 +393,23 @@ object a:
       end if
   else checkJSNativeLoadSpecOf(treePos, sym)
   end if
+<<< #4133 partial function within if-else
+val toIterator: Any => Iterator[_] = if (lenient) {
+  {
+    case i: scala.collection.Iterable[_] => i.iterator
+    case l: java.util.List[_] => l.iterator().asScala
+    case a: Array[_] => a.iterator
+    case o => unsupportedCollectionType(o.getClass)
+  }
+} else {
+  unsupportedCollectionType(tag.runtimeClass)
+}
+>>>
+val toIterator: Any => Iterator[_] = if (lenient) {
+  case i: scala.collection.Iterable[_] => i.iterator
+  case l: java.util.List[_]            => l.iterator().asScala
+  case a: Array[_]                     => a.iterator
+  case o                               => unsupportedCollectionType(o.getClass)
+}
+else
+  unsupportedCollectionType(tag.runtimeClass)