José Mourinho and Manchester United suffered another embarrassing defeat on Saturday when Manuel Pellegrini's West Ham United claimed a famous 3-1 win over the Red Devils, capping off a forgettable week for Mourinho's charges.

What's the story?

United host Valencia at Old Trafford in the Champions League on Tuesday evening and the Portuguese manager and his side will have it all to play for if they were to get their season back on track. United were held to a 1-1 draw by Wolverhampton Wanderers last weekend and were then knocked out of the Carabao Cup on penalties by Frank Lampard's Derby County last week Tuesday, all before their encounter with the Hammers.

Mark Noble challenges Paul Pogba during West Ham United v Manchester United

United thus will have to be very careful if they want to avoid another poor performance against Valencia. Mourinho's men made a strong start to the competition, beating Young Boys 3-0 in the opening round, but a win over the Spanish side on Tuesday is almost a must, given the fact that they also have Italian giants Juventus in their group to face.

But the United boss will have to make a couple of tactical changes if they were do that, including a change in formation compared to Saturday where Mourinho opted for five defenders at the back, with midfielder Scott McTominay operating as a centre-back.

What changes to make?

The obvious decision for Mourinho would be to go back to four defenders at the back and adding an extra attacker to the starting XI in a 4-3-3 formation. Portuguese right-back Diogo Dalot had a very solid debut against Young Boys and should replace Ashley Young after a really poor performance by the England international at West Ham.

Ashley Young celebrates scoring a goal for Manchester United

Whether Paul Pogba features in the starting team remains to be seen after the Frenchman was subbed off in the 70th minute on Saturday in what was turbulent week for him and Mourinho. Nonetheless, the gaffer should make space for Fred in the midfield with either Pogba, Marouane Fellaini or Nemanja Matic being dropped. The Brazilian has proved to be quiet but composed so far this season, something United will need on Tuesday.

Other than that Mourinho should think about giving Alexis Sanchez or Anthony Martial a start on the left-wing, alongside Marcus Rashford and Romelu Lukaku. Rashford was the only United player that looked genuinely threatening against West Ham after coming on in the 57th minute, and he would could cause problems for the Valencia defenders if playing as part of a front three.