Don't think I'd trust Sanchez with a man-marking job to be honest
Because...?
Sanchez isn’t showing a lot of quality but he has maintained an ability and willingness to work and press within the team’s shape. His reaction upon losing possession has been the most consistently positive feature of his time here. Placing him centrally, and matching him up against a sitting midfielder who is not going to cover the same ground as a typical full back will, gives him a very realistic chance of excelling in his defensive tasks.
Your idea of man-marking must be different from mine. Being tasked with marking an opponent happens to basically all our players all the time. It doesn’t stop Pogba from being creative because it’s a completely different phase of play - he can’t be creative when we’re defending, because we don’t have the ball.
Also, Jorginho is struggling. We’re not talking about Pirlo or Fabregas, or a player like de Jong who’s going to storm forward with the ball at his feet. How we deal with Hazard, however, may well decide the game.