Alexis Sanchez leaving Arsenal to join Manchester United was a mistake, says Robert Pires
The Chile star spent four years at the Emirates, scoring 80 goals in 166 appearances for the Gunners and helping the club win two FA Cups.
But he completed a controversial move to Old Trafford last January in a deal that saw Henrikh Mkhitaryan head in the opposite direction.
Much was expected of Sanchez following his arrival at United but the 29-year-old has endured a difficult period, netting just four goals in 26 games.
The Chilean has lost his place in Jose Mourinhos starting line-up and Pires says he should have stayed at Arsenal.
Honestly, it surprised me, Pires told Chilean newspaper El Mercurio when asked about Sanchezs departure from the Emirates.
For me, Sanchez had to stay at Arsenal, where he was one of our stars.
I dont know if he could say no to United, but I think the style of play of the London club suits his performances better. But you have to respect his decision.
Pires added: Alexis was very good, hes an excellent footballer, but I also got to know him as a person and I can say that I loved knowing him, he is a friend.
He stands out for his professionalism and that helped Arsenal to win several trophies.
Pires also discussed Sanchezs difficult spell at Manchester United and said he might have to leave the club in January to revive his career.
Hes going through a complex moment, he added.
The relationship with the manager is always important, but its notable that there are complications between José Mourinho and him.
When youre a United manager and you have players like Paul Pogba and Sanchez, you have to take care of them, because in the end the only important thing is for the team to win.
When there are problems, the most important and complicated thing, at the same time, is to sit down to talk and say things face to face.
Sanchez doesnt deserve to be on the bench or stay at home.
Well see if he finds a solution in January, because he is not playing and he has to do it, since he is a wonderful footballer.