Manchester United manager David Moyes feels his side might fall short in the Champions League this season.
The Red Devils have suffered their customary poor start to the league season, and although the 50-year old believes the squad is good enough to defend their Premier League crown, he feels they may be short of the required quality needed to conquer Europe.
He said: "To win the Champions League you have to have five or six world class players.
"If you look at Bayern Munich, they have five or six really world-class players, and to win it you might have to have that in your squad.
"Look at Barcelona, who had it in the past, and Real Madrid have maybe got it now.
"That's the level you have to get at to win it. We've not got that yet."
He added: "What we have got is experience and several players who are in that category or close to it."
United also have a tough group to negotiate, and they will be hoping to bounce back from the defeat at home to West Brom when they travel to Ukraine to face Shakhtar Donetsk on Wednesday night.
Speaking after the shock loss at Old Trafford to the Baggies - who hadn't won there for 35 years prior to Saturday's game - Moyes was critical of the performance but believes it is too early to write off their title hopes.and admitted his side deserved to lose.
"This is a great club and we have a great team - and the fans can be sure that we will do everything to put this right," he said.
“I am concerned - but only because we aren’t playing well. There’s a lot of games left and it isn’t because of a lack of trying.
“It was a poor performance and a poor result. I can’t argue that West Brom were the better team and deserved their victory.
“After beating Liverpool in midweek, I wanted us to gain some momentum. But we lacked any spark. We had a lot of possession in the first half, but just didn’t create enough chances.”