diff --git a/src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php b/src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php
index 32a007573e5d..37cb55fe36c7 100644
--- a/src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php
+++ b/src/Illuminate/Database/Eloquent/Concerns/QueriesRelationships.php
@@ -12,6 +12,7 @@
 use Illuminate\Database\Eloquent\Relations\Relation;
 use Illuminate\Database\Query\Builder as QueryBuilder;
 use Illuminate\Database\Query\Expression;
+use Illuminate\Support\Casing;
 use Illuminate\Support\Str;
 use InvalidArgumentException;
 
@@ -627,7 +628,7 @@ public function withAggregate($relations, $column, $function = null)
 
             unset($alias);
 
-            if (count($segments) === 3 && Str::lower($segments[1]) === 'as') {
+            if (count($segments) === 3 && Casing::lower($segments[1]) === 'as') {
                 [$name, $alias] = [$segments[0], $segments[2]];
             }
 
diff --git a/src/Illuminate/Foundation/Console/DocsCommand.php b/src/Illuminate/Foundation/Console/DocsCommand.php
index b8a36749ec2d..af9035ad87fc 100644
--- a/src/Illuminate/Foundation/Console/DocsCommand.php
+++ b/src/Illuminate/Foundation/Console/DocsCommand.php
@@ -7,6 +7,7 @@
 use Illuminate\Contracts\Cache\Repository as Cache;
 use Illuminate\Http\Client\Factory as Http;
 use Illuminate\Support\Arr;
+use Illuminate\Support\Casing;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Env;
 use Illuminate\Support\Str;
@@ -235,15 +236,15 @@ protected function askForPageViaAutocomplete()
             label: 'Which page would you like to open?',
             options: fn ($value) => $this->pages()
                 ->mapWithKeys(fn ($option) => [
-                    Str::lower($option['title']) => $option['title'],
+                    Casing::lower($option['title']) => $option['title'],
                 ])
-                ->filter(fn ($title) => str_contains(Str::lower($title), Str::lower($value)))
+                ->filter(fn ($title) => str_contains(Casing::lower($title), Casing::lower($value)))
                 ->all(),
             placeholder: 'E.g. Collections'
         );
 
         return $this->pages()->filter(
-            fn ($page) => $page['title'] === $choice || Str::lower($page['title']) === $choice
+            fn ($page) => $page['title'] === $choice || Casing::lower($page['title']) === $choice
         )->keys()->first() ?: $this->guessPage($choice);
     }
 
diff --git a/src/Illuminate/Foundation/Console/ViewMakeCommand.php b/src/Illuminate/Foundation/Console/ViewMakeCommand.php
index 3f8e4da6a639..6f91520af7c4 100644
--- a/src/Illuminate/Foundation/Console/ViewMakeCommand.php
+++ b/src/Illuminate/Foundation/Console/ViewMakeCommand.php
@@ -5,6 +5,7 @@
 use Illuminate\Console\Concerns\CreatesMatchingTest;
 use Illuminate\Console\GeneratorCommand;
 use Illuminate\Foundation\Inspiring;
+use Illuminate\Support\Casing;
 use Illuminate\Support\Facades\File;
 use Illuminate\Support\Str;
 use Symfony\Component\Console\Attribute\AsCommand;
@@ -181,7 +182,7 @@ protected function testClassName()
      */
     protected function testClassFullyQualifiedName()
     {
-        $name = Str::of(Str::lower($this->getNameInput()))->replace('.'.$this->option('extension'), '');
+        $name = Str::of(Casing::lower($this->getNameInput()))->replace('.'.$this->option('extension'), '');
 
         $namespacedName = Str::of(
             Str::of($name)
diff --git a/src/Illuminate/Support/Stringable.php b/src/Illuminate/Support/Stringable.php
index 6ae57e032066..b920e3568c32 100644
--- a/src/Illuminate/Support/Stringable.php
+++ b/src/Illuminate/Support/Stringable.php
@@ -459,7 +459,7 @@ public function limit($limit = 100, $end = '...', $preserveWords = false)
      */
     public function lower()
     {
-        return new static(Str::lower($this->value));
+        return new static(Casing::lower($this->value));
     }
 
     /**
diff --git a/src/Illuminate/Validation/Concerns/ValidatesAttributes.php b/src/Illuminate/Validation/Concerns/ValidatesAttributes.php
index 5628e43783c9..522d2e1da4ef 100644
--- a/src/Illuminate/Validation/Concerns/ValidatesAttributes.php
+++ b/src/Illuminate/Validation/Concerns/ValidatesAttributes.php
@@ -18,6 +18,7 @@
 use Illuminate\Container\Container;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Support\Arr;
+use Illuminate\Support\Casing;
 use Illuminate\Support\Exceptions\MathException;
 use Illuminate\Support\Facades\Date;
 use Illuminate\Support\Str;
@@ -1353,7 +1354,7 @@ public function validateLte($attribute, $value, $parameters)
      */
     public function validateLowercase($attribute, $value, $parameters)
     {
-        return Str::lower($value) === $value;
+        return Casing::lower($value) === $value;
     }
 
     /**
@@ -1366,7 +1367,7 @@ public function validateLowercase($attribute, $value, $parameters)
      */
     public function validateUppercase($attribute, $value, $parameters)
     {
-        return Str::upper($value) === $value;
+        return Casing::upper($value) === $value;
     }
 
     /**
@@ -2290,7 +2291,7 @@ protected function convertValuesToBoolean($values)
     protected function convertValuesToNull($values)
     {
         return array_map(function ($value) {
-            return Str::lower($value) === 'null' ? null : $value;
+            return Casing::lower($value) === 'null' ? null : $value;
         }, $values);
     }