(AFP) - Manchester United manager Louis van Gaal is at risk of a knockout punch as his side visit Stoke City in the weightiest fixture of the Premier League's jam-packed Saturday programme.

The 64-year-old Dutchman is reportedly one or two bad results away from the sack after a run of six winless games that has seen his team drop to fifth place in the Premier League and exit the Champions League.

Amid intense speculation that he is on the brink of being replaced by Jose Mourinho, van Gaal stormed out of his pre-game press conference after just five minutes, wishing stunned reporters an ironic "Merry Christmas".

In a subsequent interview with MUTV, he acknowledged that the trip to Stoke was a "must-win game".

"When you have lost three times in a row, then you need a victory. We have focused ourselves to do that, but it is not easy," he said.

"Stoke City have won against Manchester City, for example, and it's a special ground. It is not easy with a lot of circumstances that are not suitable always to playing good football."

Stoke's draughty Britannia Stadium is a forbidding place at the best of times and it has proved particularly hostile of late, with Chelsea and Manchester City among the visiting teams to have succumbed to Mark Hughes's side.

Hughes, a former United striker, expects Van Gaal to turn the situation around, but is unsentimental about the prospect of adding to the Dutchman's woes.

"They have got good players, they have got a good squad," said the Welshman, whose side have won only one of their last four league games.

Publicly, at least, van Gaal retains the support of his players as he attempts to lift a side who have fallen nine points behind leaders Leicester ahead of the Boxing Day programme.

"It's not nice when you're getting criticised after every game," said captain Wayne Rooney.

"It's tough for the players to deal with. We get hurt because we're proud people and proud to play for Manchester United. When it's not going right, it's hard to take and frustrating."