Alexis Sanchez has completed his move to Manchester United from Arsenal, with Henrikh Mkhitaryan heading the other way in one of the most high-profile swap moves of all time.

The finishing touches to the deal were made on Monday and an announcement that the two 29-year-olds had traded places was made at 6pm.

United’s new number seven Sanchez, who missed Arsenal’s win over Crystal Palace on Saturday while negotiations over a switch continued, posted a departing message on Instagram where he took aim at ex-Arsenal players that have been critical of him.

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

A post shared by Alexis Sanchez (@alexis_officia1) on

Though his social-media post did not reference anyone directly, Sanchez wrote: “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.”

Martin Keown, a former Gunners defender, had called Sanchez “the biggest mercenary in football”, with reports suggesting the Chilean forward will earn £500,000 a week at Old Trafford.

United’s rivals Manchester City had tried to sign Sanchez in the summer and revisited the possibility in this window only to pull out due to the rising costs.

Arsenal wanted £35million for a player out of contract in the summer and United’s willingness to meet Sanchez’s wage demands and use a makeweight in Mkhitaryan, who is valued at the Gunners’ asking price, allowed a straight swap to take place.

“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 boss Mourinho lauded the acquisition of Sanchez, adding: “Alexis is one of the best attacking players in the world and he will complete our very young and talented group of attacking players.

“He will bring his ambition, drive and personality, qualities that make a Manchester United player and a player that makes the team stronger and the supporters proud of their club dimension and prestige.”

In his Instagram post, Sanchez also referenced speaking to Thierry Henry, who left Arsenal 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,” Sanchez added.

Mkhitaryan was one of Mourinho’s first signings in the summer of 2016 and scored 11 times in his debut season, including one goal in the Europa League final victory over Ajax.

However, he was deemed surplus to requirements by the United boss once the opportunity to sign Sanchez became available in this window.

“Henrikh is a very complete player,” Wenger said on arsenal.com. “He creates chances, he defends well, he can absorb distances and he’s very committed as well. I must say he’s a player who has all the attributes.”