Manchester United goalkeeper David de Sea has warned his teammates ahead of the second leg clash with Barcelona in the Champions League quarter-finals, following their unconvincing show against West Ham in the Premier League.
Manchester United will take a trip to Spain to play Barcelona at the Camp Nou in a bid to advance to the Champions League semifinals.
Barcelona suffered a 1-0 defeat at Old Trafford on Wednesday in the first leg and they need to be at their best to overcome the deficit.
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De Gea said: "Of course it's difficult, but if you want to be a top team you have to play big Champions League games, and the weekend after it's the Premier League.
"So you have to be focused and ready for a difficult game again. I think we didn't play well [against West Ham], we have to improve a lot and now we have a big challenge on Tuesday.
"We will try to fight and win the game. We can go with more confidence after the three points.
"It's a big challenge, a special occasion, in Spain, against Barcelona, a Champions League night, so it's going to be an amazing game.
"We're happy with the win, but at the same time we have to improve a lot."