Alexis Sanchez will wear the number 7 shirt at Manchester United after completing his move from Arsenal

Alexis Sanchez finally became a Manchester United player yesterday as Henrikh Mkhitaryan moves to Arsenal in exhange. The Chile international is available to make his United debut away to Yeovil Town in the FA Cup on Friday night. It's a massive boost to Jose Mourinho's squad as United move closer to their Champions League last 16 tie against Sevilla. Sanchez is the type of player United need in the big games against their Premier League rivals.

The 29 year old has signed a four-and-a-half-year deal and will become the top earner at the club but the money isn't an issue for United, who have retained their position as world football's top earners. I understand the concerns some people may have about Sanchez becoming the club's highest earner and the possibility of it leading to discontent in dressing room. It won't take long for the United players to realise what an asset Sanchez is.

Mourinho now has to decide where to play the former Arsenal forward. Sanchez has operated on the left hand side for the Gunners but he could play in any attacking position and the player himself said he's willing to do that. Anthony Martial has scored in his last three league games from the left hand side so it would be hard to leave the France international out on current form and the same could be said for Jesse Lingard who has been so impressive since the end of November. That means Marcus Rashford and Juan Mata look set to lose out because it's hard to imagine Romelu Lukaku being dropped.

United's most trusted formation is a 4-2-3-1 with Nemanja Matic and Paul Pogba the two players in central midfield. Sanchez could play as any one of the three players behind Lukaku and he could even play in the Lukaku role if necessary. Sanchez could be exactly what Lukaku needs because the Belgian has been isolated at times against some of the other clubs in the top six. United go to Wembley next week to face Tottenham so Mourinho's team selection should tell us all we need to know. Where will Sanchez play and who will be the player to make way?