Bayern Munich winger Arjen Robben says they must not underestimate Champions League opponents Manchester United.

Robben insists United will still be dangerous without Robin van Persie.

"It's a shame that he's (Van Persie) going to miss out," Robben said. "Everybody wants to be involved when you get towards the end of the season and it's painful when you can't be - and I know that from experience.

"Of course Van Persie has particular quality, but Manchester still have enough options up front: Rooney, Welbeck, Nani, Valencia.

"Like I said, it's going to be a difficult duel, but we're all really looking forward to it."