Manchester United striker Ruud van Nistelrooy has admitted that the club's loss of form is down in part to David Beckham's transfer to Real Madrid.
United lost ground to Premiership leaders Arsenal following a 1-1 draw at home to lowly Leeds on Saturday.
And Van Nistelrooy said that Beckham's influence in midfield has been missed.
"Becks is a missed here at United as a player as well as a person," he said. "From what I've seen of him in Spain, he's doing really well."
Speaking to Uefa's official website, he added: "With the language barrier, it's not easy for a player to make a move like that.
"But Becks has put in some great performances for Real."
Van Nistelrooy has continued to find the net regularly for Manchester United, who trail Arsenal by seven points in the league.
But the Old Trafford club have still faltered and face a minor injury crisis ahead of Wednesday's Champions League game at Porto.
And Van Nistelrooy is well aware that the Portuguese side have the ability to cause United problems.
"They are very strong at home as they showed against Real Madrid in the group stages," the Dutchman said.
"Winning the Uefa Cup last year will have lifted everybody at the club and it will be a huge task over the two games.
"No game is easy at this level. We will need a good result over there but it will be hard."
Van Nistelrooy also had words of praise for one of his chief rivals for the mantle of Europe's top striker - Thierry Henry of Arsenal.
The two Premiership frontmen have been named in Uefa.com's Team of 2003 - news that had Van Nistelrooy contemplating the mouthwatering prospect of actually playing alongside the Frenchman.
"Henry is a great player," the United star said. "I think we could do well together.
"He has everything a striker needs to have and he proves that week in week out here in England and for France."