Last updated on .From the section Football

Phil Jones (second left) grimaces after a tackle by Chris Smalling (centre) during training

Manchester United's injury problems have worsened, with midfielder Juan Mata joining defenders Chris Smalling and Phil Jones on the sidelines.

United announced on Friday that Mata, 28, has had surgery on a groin problem.

Jones, 25, injured a toe in an innocuous training-ground tackle, with reports claiming it involved Smalling. external-link

Smalling, 27, has been pictured wearing a leg brace external-link , and United manager Jose Mourinho said both central defenders would be out "long term".

The club are yet to reveal how long Mata will be out for, and said updates on his recovery "will follow in due course".

Captain Wayne Rooney returns for Saturday's Premier League game against West Brom (15:00 BST) after recovering from a knee injury.

The 31-year-old has missed the Red Devils' past four games.

But United will be without striker Zlatan Ibrahimovic and midfielder Ander Herrera, who are both suspended, and midfielder Paul Pogba, who has a hamstring problem.

Asked how long he expects to be without Jones and Smalling, Mourinho: "I don't know. I think clearly they are long-term injuries, and Pogba I have no idea."

'One defeat and we're out of it'

Mourinho has previously said he would concentrate on United's Europa League campaign and a two-legged quarter-final against Belgian team Anderlecht next month, rather than the league.

However, as United are four points behind Liverpool, who occupy the fourth Champions League qualifying place and have two games in hand, he is not abandoning the league.

"Every match now for us is a big match," he said.

"Europa League is play quarter-final or go home, in the Premier League one more match, one more victory we are in the run, one defeat maybe you are not in the run any more."

'I am sorry for what I did to him'

Manchester United: Jose Mourinho 'regrets' Bastian Schweinsteiger treatment

Mourinho also said he regretted the way he treated Bastian Schweinsteiger, and added he apologised to the midfielder before his move to the Chicago Fire.

The German World Cup winner, who joined United in 2015, trained with the reserves following Mourinho's arrival in the summer, but was brought back into the first team in late October.

However, last week the 32-year-old was permitted a move to join the MLS side.

"He's in the category of players that I feel sorry for something that I did to him," Mourinho said.

"The last thing I told him before he left: 'I was not right with you once, I have to be right with you now.'

"So when he was asking me to let him leave, I had to say 'yes, you can leave' because I did it once, I cannot do it twice.

"I will miss a good guy, a good professional, a good influence in training - a very good influence."