Former Manchester United defender Denis Irwin has said that the Red Devils will need to deal with Robert Lewandowski in order to stand a chance of picking up a positive result against Barcelona.
The 20-time English champions will head to Camp Nou for the first leg of their Europa League knockout round playoff on Thursday evening before the reverse fixture at Old Trafford next week.
Irwin, who played at Camp Nou on three occasions during his professional career, has said that the Man United defenders will need to be "on their toes" to deal with the Poland international.
"There's no doubt that the centre-halves, whoever plays, are well aware of his capabilities," Irwin told Man United's official website.
"He's had a fantastic career. He was brilliant at Bayern Munich and it took him a long time to get the plaudits that he deserved.
"He's doing it again at Barcelona and playing very well. He's got great experience - he's one of those players that it doesn't matter what age, he will always score goals.
"Our defenders, particularly the two centre-halves, will have to be on their toes. But Barcelona as a whole are a great attacking team, they score plenty of goals.
"Whoever plays in that defence will have to play as a unit and make sure that we don't concede too many chances."
Lewandowski made the move to Barcelona from Bayern last summer, and he has been in impressive form for the Catalan side this season, scoring 23 goals and registering six assists in 27 appearances.
The 34-year-old netted five times in five matches in the group stage of the Champions League, but Xavi's side failed to qualify for the knockout round of the competition.
Lewandowski has only played in the Europa League on six previous occasions, all of which came during his time at Borussia Dortmund, while he has netted just once in the competition.
Man United will be without the services of one of their first-choice central defenders on Thursday, as Lisandro Martinez is suspended following his booking against Real Sociedad in the competition last time out.
As a result, Red Devils head coach Erik ten Hag must decide whether to bring in Harry Maguire, Victor Lindelof or Luke Shaw alongside Raphael Varane, or switch to a back five for the first leg of the European clash. body check tags ::