Ernesto Valverde has warned his Barcelona players that they cannot afford to take "powerful" Manchester United lightly in their Champions League quarter-final clash.
The reigning Spanish champions head into Wednesday evening's first leg at Old Trafford on the back of a late 2-0 win over Atletico Madrid this weekend, increasing their lead at the top of La Liga to 11 points.
Barca are favourites to progress from their last-eight tie with United, but Valverde believes that the Red Devils - beaten 2-1 by Wolverhampton Wanderers in their most recent outing - have strengths that are difficult to cope with.
"They are a powerful team. They are going through a good run, even if they lost their last match," Sky Sports News quotes him as saying.
"Physically they are really strong and they know how to put pressure on their opponents. They have players who are physically very powerful, and they can be dangerous strategically as well.
"This match is a classic in European football. Barcelona have never won at Old Trafford I believe and we are going to try and change that."
Barcelona have lost two and drawn two of their previous four trips to Old Trafford, with their most recent match there ending in a 1-0 defeat in the second leg of the 2007-08 Champions League semi-finals.
