United won 1-0 at Craven Cottage.
"United are champions if they can win games like that," said Riether, on loan from Cologne. "It's just the same with Bayern Munich. Sometimes you play against them and you think you've done well in the game, created chances, but in the end they win 1-0. That's a good team.
"Some of it is in the head. It's experience, it's the great players they have. They know that they can always score. They don't need a lot of chances. They have one chance in the second half, and they score a goal. That's perfect."