The Champions League quarter-final is delicately poised following a 1-1 draw in the first leg at Old Trafford, and Boateng was eager to talk about Rooney's importance as concerns about the striker missing the match became the main talking point.
"I don't think he will miss the return," the German told the club's official website. "But if it's true, it would certainly be a big loss for United.
"Rooney is the key man for United. He always makes himself available, he goes looking for the ball, he takes the free kicks and corners and he's always good for a goal"