Gerard Pique does not want Barcelona to underestimate Manchester United.

The Catalan defender, who was at United as a young player, believes the Red Devils have enough weapons to hurt his side.

And Pique wants to ensure they get a positive result at Old Trafford, which does not give United too much hope for the second leg at the Nou Camp.

"I've seen the replay of Manchester United v PSG," he told a media conference ahead of the game.

"It's a good example.

"You can never leave Manchester United unmarked. You've got to finish off the job. They showed that in the second leg against PSG.

"They've got a lot of good young players. The penalty at the end is a big example of what can happen. We know how dangerous United are."