The Red Devils won their final game of last season at The Stadium of Light.
But then news came through that Sergio Aguero’s last-ditch goal for Manchester City had snatched the title away from them.
Sunderland fans cheered and taunted United with a City-style ‘Poznan’ celebration.
But Rooney warned: “If there is one team I want to beat this season it will be Sunderland.
“For them to be cheering like that was sad. It was something I and a lot of the players won’t forget.”