Jose Mourinho
Jose Mourinho was sacked from his job at Chelsea in DecemberGetty

Former Chelsea manager Jose Mourinho has written a six-page letter to Manchester United and has expressed his desire to be their next manager. Louis van Gaal is the current boss at Old Trafford and the Dutchman's job at the club has come under question on several occasions this season.

Southampton's new signing Charlie Austin made a debut for the Saints against the Red Devils on 23 January. The former Queens Park Rangers striker's second half header in the final quarter saw Van Gaal's side suffer a 1-0 defeat in the league tie.

According to The Independent, the ex Barcelona and Bayern Munich manager is running out of time at United and could part ways with his employers in the summer. Mourinho was sacked by Chelsea in December and has set his sights on managing the 20-time English champions.

The Portuguese tactician's agent Jorge Mendes has reportedly contacted the United board to discuss the possibility of his client replacing Van Gaal, when the latter's time is up. Following his side's defeat to Southampton, the 64-year-old coach admitted the fans' reaction at Old Trafford was justified and it was the worst he has faced since taking the job in 2014.

"Yes. It was very clear I think [fans' reaction]. I can imagine [why]. I've also seen a poor match," Van Gaal explained, as quoted by the Daily Mail.

"It was a poor performance of course. Football is not only defending but also creating chances. We didn't create any chances. I cannot change that feeling. I can only work hard with my players to improve our game. That is what I'm doing. I'm disappointed," he said.

In the letter written by Mourinho, the former Chelsea manager has explained his willingness to adapt to the Red Devils' principles and style of play. He has also explained the areas where United need to strengthen and suggested on signings that need to be done to improve the squad.

It should be seen whether United will appoint Mourinho or will they make an approach for Pep Guardiola, who has already confirmed he will leave Bayern Munich after the end of the season. The Spaniard has already admitted that he would like to manage a club in the Premier League and United's league rivals City are also believed to be interested in his services.