diff --git a/core/modules/aggregator/aggregator.admin.inc b/core/modules/aggregator/aggregator.admin.inc
index f87d9a0..632f1ec 100644
--- a/core/modules/aggregator/aggregator.admin.inc
+++ b/core/modules/aggregator/aggregator.admin.inc
@@ -6,7 +6,6 @@
  */
 
 use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
-use Drupal\aggregator\Plugin\FetcherManager;
 use Drupal\aggregator\Plugin\Core\Entity\Feed;
 
 /**
@@ -346,7 +345,7 @@ function aggregator_admin_form($form, $form_state) {
   aggregator_sanitize_configuration();
 
   // Get all available fetchers.
-  $fetcher_manager = new FetcherManager();
+  $fetcher_manager = drupal_container()->get('plugin.manager.aggregator.fetcher');
   $fetchers = array();
   foreach ($fetcher_manager->getDefinitions() as $id => $definition) {
     $label = $definition['title'] . ' <span class="description">' . $definition['description'] . '</span>';
diff --git a/core/modules/aggregator/aggregator.module b/core/modules/aggregator/aggregator.module
index 7298e4c..6e89fde 100644
--- a/core/modules/aggregator/aggregator.module
+++ b/core/modules/aggregator/aggregator.module
@@ -5,7 +5,6 @@
  * Used to aggregate syndicated content (RSS, RDF, and Atom).
  */
 
-use Drupal\aggregator\Plugin\FetcherManager;
 use Drupal\aggregator\Plugin\Core\Entity\Feed;
 
 /**
@@ -450,7 +449,7 @@ function aggregator_refresh(Feed $feed) {
   list($fetcher, $parser, $processors) = _aggregator_get_variables();
 
   // Fetch the feed.
-  $fetcher_manager = new FetcherManager();
+  $fetcher_manager = drupal_container()->get('plugin.manager.aggregator.fetcher');
   try {
     $success = $fetcher_manager->createInstance($fetcher)->fetch($feed);
   }
diff --git a/core/modules/block/lib/Drupal/block/Plugin/system/plugin_ui/BlockPluginUI.php b/core/modules/block/lib/Drupal/block/Plugin/system/plugin_ui/BlockPluginUI.php
index 740b349..5beb482 100644
--- a/core/modules/block/lib/Drupal/block/Plugin/system/plugin_ui/BlockPluginUI.php
+++ b/core/modules/block/lib/Drupal/block/Plugin/system/plugin_ui/BlockPluginUI.php
@@ -24,7 +24,7 @@
  *     "module" = @Translation("Modules")
  *   },
  *   link_title = @Translation("Configure block"),
- *   manager = "Drupal\block\Plugin\Type\BlockManager",
+ *   manager = "plugin.manager.block",
  *   menu = TRUE,
  *   path = "admin/structure/block/list",
  *   suffix = "add",
@@ -46,7 +46,8 @@ public function form($form, &$form_state, $facet = NULL) {
     // @todo Add an inline comment here.
     list($plugin, $theme) = explode(':', $this->getPluginId());
     $plugin_definition = $this->getDefinition();
-    $manager = new $plugin_definition['manager']();
+    // @todo Find out how to let the manager be injected into the class.
+    $manager = drupal_container()->get($plugin_definition['manager']);
     $plugins = $manager->getDefinitions();
     $form['#theme'] = 'system_plugin_ui_form';
     $form['theme'] = array(
diff --git a/core/modules/system/lib/Drupal/system/Plugin/PluginUIBase.php b/core/modules/system/lib/Drupal/system/Plugin/PluginUIBase.php
index f2c312d..dd890fd 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/PluginUIBase.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/PluginUIBase.php
@@ -22,7 +22,13 @@
    */
   public function form($form, &$form_state) {
     $plugin_definition = $this->getDefinition();
-    $manager = new $plugin_definition['manager']();
+    // @todo Find out how to let the manager be injected into the class.
+    if (class_exists($plugin_definition['manager'])) {
+      $manager = new $plugin_definition['manager']();
+    }
+    else {
+      $manager = drupal_container()->get($plugin_definition['manager']);
+    }
     $plugins = $manager->getDefinitions();
 
     $rows = array();