Alexis Sanchez sealed his switch from Arsenal to Manchester United and then hit back at former Gunners players who have criticised him.

One of the most high-profile swap deals ever was finally completed on Monday as Sanchez and Henrikh Mkhitaryan, both 29, traded places.

Upon becoming a member of Jose Mourinho’s squad, Chilean forward Sanchez, who had been a target for United’s rivals Manchester City both in the summer and earlier this window, said: “I am thrilled to be joining the biggest club in the world.”

Last week ex-Arsenal defender Martin Keown had branded Sanchez “the biggest mercenary in football”, while Keown’s old team-mate Ian Wright claimed he had “clocked off” in December.

Quiero agradecer al Staff Técnico, al equipo médico, a todos los compañeros con los que compartí muchas cosas lindas para el club y en especial a todas esas personas que no se ven en las portadas, pero que sin ellos nada seria posible, que son los que te preparan la comida y te cuidan día día, los que nos mantienen los zapatos limpios y campos de fútbol en las mejores condiciones para entrenar. Mil gracias a Ustedes por ayudarnos a mejorar cada día. Gracias por tanto cariño 😢. Hay personas (ex jugadores del club) que han hablado sin conocimiento de lo que ocurre en la interna y causan daño. Debo decir que siempre me entregué al 100%, hasta el último día, en que le pedí al Mister estar con el equipo, por que quería ser un aporte. Recuerdo hoy, una conversación que tuve con Henry, un histórico de Arsenal, que cambió de club, por la misma razón que hoy me toca a mi. Gracias por todo Gunners ! I want to say thanks to the Technical Staff, to the medical team and all teammates with whom I shared many nice things for the club and especially those people who do not see themselves on the covers, but without them nothing would be possible, which are there to prepare food for us and take care of us day by day, those who keep our shoes clean and the grass in the best conditions. Many thanks to you for helping us to improve every day. Thank you very much 😢. There are people (former club players) who have spoken with no knowledge of what happens inside the club and cause damage. I must say I always gave 100%, until the last day, when I asked to the Mister to be in the team, because I wanted to be a contribution. I remember today, a conversation I had with Henry, a historic Arsenal player, who changed club for the same reason and today is my turn. Thanks for everything Gunners! All we achieved and the good moments that I gave to the club, I want to dedicate it to the fans, they are the most important. Thanks for every time you sing Alexis Sanchez Baby

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Though he did not directly reference anyone in particular, Sanchez took aim at his critics in part of a farewell Instagram post that read: “There are people (former club players) who have spoken with no knowledge of what happens inside the club and cause damage.

“I must say I always gave 100%, until the last day, when I asked to the Mister (Arsenal manager Arsene Wenger) to be in the team, because I wanted to be a contribution.”

Sanchez claimed he had spoken to another former Arsenal player Thierry Henry and remarked how his departure was similar to the one the Frenchman made when leaving for Barcelona in 2007.

“I remember today, a conversation I had with Henry, a historic Arsenal player, who changed club for the same reason and today is my turn,” he added.

Premier League leaders City had tried to sign Sanchez in the summer and were expected to be the front runners to land him this month when it became apparent he wanted to leave ahead of his Arsenal contract expiring in the summer.

However, Pep Guardiola’s club were reluctant to pay both the £35million asking price and the wages Sanchez was requesting.

That allowed United to swoop and the fact they were able to offer Mkhitaryan in return meant the deal could be done as a straight swap.

“Since I was a young lad I’ve always said that my dream was to play for Manchester United, and I’m not just saying that because I’m here now and today it’s come true,” Sanchez told MUTV.

“I always said as a kid that I’d like to play for United and I once spoke to Sir Alex Ferguson about it. We chatted for around 20 minutes. And I told him that my dream was to come here to Manchester United.

“It really is a massive club, very powerful, and so now when I got the opportunity to come here I looked at the badge and my hairs just stood up on end because it’s a powerful club and the biggest in England.”

United’s latest signing also revealed boss Mourinho had a big influence in him deciding he wanted a switch to Old Trafford.

“He indicated it is important for the club for me to be here,” Sanchez added of Mourinho.

“I also believe that the club itself cared about me joining, and I got the impression that they were keen for me to come here and wear the number seven shirt. I think that also gets through to the player.

“Players sometimes need to feel important and loved by the club. That was one of the things that attracted me to come here, along with the manager, who is a person who won everything in Italy, the same as he did in Spain, and he’s a manager who likes to win.”