The Red Devils have been besieged by issues during a difficult second season for the Dutchman, with the side struggling in the Premier League and dumped out of Europe before Christmas.

United face an uphill battle to qualify for next year's Champions League and produced one of their worst displays on Saturday at Brentford, where Victor Lindelof became the latest player to pick up a muscle injury.

The Sweden international's hamstring issue in the 1-1 draw is set to keep him out for at least a month, with his replacement Lisandro Martinez facing a similar absence after sustaining a calf complaint in training.

Those issues compound the absence of fellow defenders Luke Shaw and Tyrell Malacia, but Ten Hag is hopeful that Varane - who went off at half-time on Saturday - and recently injured Evans will be fit to face Chelsea.

"No more issues - we don't need (anymore)!" the United manager said ahead of Thursday's match. "On the frontline and in midfield we are OK, we have options there.

"But in the backline we have a lack of options, but the good thing is back in training this afternoon is Raphael Varane and Jonny Evans. And Harry Maguire was already yesterday back in training."

Lindelof and Martinez's setbacks raise further questions about the spate of muscle injuries United have been dealing with this term.

Asked if they are any closer to knowing why they are getting so many issues, Ten Hag said: "Yeah, we have an idea but we will work on that. I think internally we will deal with it."

Ten Hag rejected the chance to expand on what that "idea" was but was more forthcoming about the strains on top teams right now.

"You can't prevent," the United boss said. "You see it's not only us who've had this.

"The standards of the Premier League from an intensity perspective are so high, the overload in the schedule, also international football is so huge.

"We have all internationals in our squad and you see it's not only us - City, Liverpool and Newcastle have the problems, so there are many other teams.

"In this moment, especially the defending department but in the midfield and frontline the players are available."

Injuries only offer some mitigation for United's struggles, though, with the drop-off from the stunning FA Cup quarter-final win against Liverpool to the draw at Brentford setting off alarm bells.

The Bees had an eye-watering 31 shots on Saturday and the Red Devils return to west London on Thursday needing a vastly improved display.

"I am long enough in football to know and also some of you should also understand why such things happen," Ten Hag said.

"Sometimes you are not playing well but we are Man United and we still have to win. And when you are winning, you can't give it away like we did.

"That was the biggest disappointment for me but also we have to see the trend-line over a long period, from Christmas on, is positive and we keep going."

The only positive at Brentford was Mason Mount scoring his first United goal as he continues to build fitness after four months out with a calf issue.

The 25-year-old is now preparing for his first return to Chelsea since leaving in the summer, with Ten Hag keen to avoid rushing him back too soon.

"He's a fantastic football player but it's important first that he is getting and keeping fit because he has had three injuries," he said.

"You see it now with Licha, so another injury, so you want to avoid and we have to do this carefully.

"This is first objective, to keep him fit. Of course in the same we want to use him that he can benefit and contribute to the team like he did on Saturday when he had a big impact."

Man Utd to have Raphael Varane and Jonny Evans back for Chelsea game