The Scot clearly enjoys facing the Lancashire outfit as he has now scored six times against them in seven appearances.
His first owed much to his lightning reactions after Ali Al Habsi had turned away his header, with the second an instinctive curling strike from Adam Johnson's lay-off.
"Fletcher was fantastic," said Sunderland boss Martin O'Neill.
"It was not just his goals but also his whole centre forward play. We took great heart from his performance."