diff --git a/activerecord/lib/active_record/associations/association.rb b/activerecord/lib/active_record/associations/association.rb
index 861dda618a..7887d59aad 100644
--- a/activerecord/lib/active_record/associations/association.rb
+++ b/activerecord/lib/active_record/associations/association.rb
@@ -230,13 +230,8 @@ module ActiveRecord
         end
 
         def build_record(attributes, options)
-          attributes = (attributes || {}).reverse_merge(creation_attributes)
-
           reflection.build_association(attributes, options) do |record|
-            record.assign_attributes(
-              create_scope.except(*record.changed),
-              :without_protection => true
-            )
+            record.assign_attributes(create_scope.except(*record.changed), :without_protection => true)
           end
         end
     end
diff --git a/activerecord/test/cases/mass_assignment_security_test.rb b/activerecord/test/cases/mass_assignment_security_test.rb
index 9fff50edcb..8122857f52 100644
--- a/activerecord/test/cases/mass_assignment_security_test.rb
+++ b/activerecord/test/cases/mass_assignment_security_test.rb
@@ -50,6 +50,13 @@ module MassAssignmentTestHelpers
     assert_equal 'm',    person.gender
     assert_equal 'rides a sweet bike', person.comments
   end
+
+  def with_strict_sanitizer
+    ActiveRecord::Base.mass_assignment_sanitizer = :strict
+    yield
+  ensure
+    ActiveRecord::Base.mass_assignment_sanitizer = :logger
+  end
 end
 
 module MassAssignmentRelationTestHelpers
@@ -323,6 +330,13 @@ class MassAssignmentSecurityHasOneRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_has_one_build_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.build_best_friend(attributes_hash.except(:id, :comments))
+      assert_equal @person.id, best_friend.best_friend_id
+    end
+  end
+
   # create
 
   def test_has_one_create_with_attr_protected_attributes
@@ -350,6 +364,13 @@ class MassAssignmentSecurityHasOneRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_has_one_create_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.create_best_friend(attributes_hash.except(:id, :comments))
+      assert_equal @person.id, best_friend.best_friend_id
+    end
+  end
+
   # create!
 
   def test_has_one_create_with_bang_with_attr_protected_attributes
@@ -377,6 +398,13 @@ class MassAssignmentSecurityHasOneRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_has_one_create_with_bang_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.create_best_friend!(attributes_hash.except(:id, :comments))
+      assert_equal @person.id, best_friend.best_friend_id
+    end
+  end
+
 end
 
 
@@ -438,6 +466,13 @@ class MassAssignmentSecurityBelongsToRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_belongs_to_create_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.create_best_friend_of(attributes_hash.except(:id, :comments))
+      assert_equal best_friend.id, @person.best_friend_of_id
+    end
+  end
+
   # create!
 
   def test_belongs_to_create_with_bang_with_attr_protected_attributes
@@ -465,6 +500,13 @@ class MassAssignmentSecurityBelongsToRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_belongs_to_create_with_bang_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.create_best_friend_of!(attributes_hash.except(:id, :comments))
+      assert_equal best_friend.id, @person.best_friend_of_id
+    end
+  end
+
 end
 
 
@@ -499,6 +541,13 @@ class MassAssignmentSecurityHasManyRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_has_many_build_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.best_friends.build(attributes_hash.except(:id, :comments))
+      assert_equal @person.id, best_friend.best_friend_id
+    end
+  end
+
   # create
 
   def test_has_many_create_with_attr_protected_attributes
@@ -526,6 +575,13 @@ class MassAssignmentSecurityHasManyRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_has_many_create_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.best_friends.create(attributes_hash.except(:id, :comments))
+      assert_equal @person.id, best_friend.best_friend_id
+    end
+  end
+
   # create!
 
   def test_has_many_create_with_bang_with_attr_protected_attributes
@@ -553,6 +609,13 @@ class MassAssignmentSecurityHasManyRelationsTest < ActiveRecord::TestCase
     assert_all_attributes(best_friend)
   end
 
+  def test_has_many_create_with_bang_with_strict_sanitizer
+    with_strict_sanitizer do
+      best_friend = @person.best_friends.create!(attributes_hash.except(:id, :comments))
+      assert_equal @person.id, best_friend.best_friend_id
+    end
+  end
+
 end
 
 
diff --git a/activerecord/test/cases/nested_attributes_test.rb b/activerecord/test/cases/nested_attributes_test.rb
index 2f28dd4767..2ae9cb4888 100644
--- a/activerecord/test/cases/nested_attributes_test.rb
+++ b/activerecord/test/cases/nested_attributes_test.rb
@@ -617,11 +617,6 @@ module NestedAttributesOnACollectionAssociationTests
     assert_equal ['Grace OMalley', 'Privateers Greed'], [@child_1.name, @child_2.name]
   end
 
-  def test_should_take_a_hash_with_owner_attributes_and_assign_the_attributes_to_the_associated_model
-    @pirate.birds.create :name => 'bird', :pirate_attributes => {:id => @pirate.id.to_s, :catchphrase => 'Holla!'}
-    assert_equal 'Holla!', @pirate.reload.catchphrase
-  end
-
   def test_should_raise_RecordNotFound_if_an_id_is_given_but_doesnt_return_a_record
     assert_raise_with_message ActiveRecord::RecordNotFound, "Couldn't find #{@child_1.class.name} with ID=1234567890 for Pirate with ID=#{@pirate.id}" do
       @pirate.attributes = { association_getter => [{ :id => 1234567890 }] }
diff --git a/activerecord/test/models/person.rb b/activerecord/test/models/person.rb
index 967a3625aa..36eb08d02f 100644
--- a/activerecord/test/models/person.rb
+++ b/activerecord/test/models/person.rb
@@ -54,7 +54,7 @@ class LoosePerson < ActiveRecord::Base
   self.table_name = 'people'
   self.abstract_class = true
 
-  attr_protected :comments
+  attr_protected :comments, :best_friend_id, :best_friend_of_id
   attr_protected :as => :admin
 
   has_one    :best_friend,    :class_name => 'LoosePerson', :foreign_key => :best_friend_id
@@ -81,4 +81,4 @@ class TightPerson < ActiveRecord::Base
   accepts_nested_attributes_for :best_friend, :best_friend_of, :best_friends
 end
 
-class TightDescendant < TightPerson; end
\ No newline at end of file
+class TightDescendant < TightPerson; end