Alexis Sanchez said Monday he was "thrilled to be joining the biggest club in the world" as he moved to Manchester United from Arsenal in a swap deal with Henrikh Mkhitaryan.
The 29-year-old Chile striker, who came close to joining Manchester City last summer, has signed what is believed to be a four-and-a-half-year contract that will make him the highest-paid player in the Premier League.
It has been widely reported that Sanchez will earn a pre-tax salary of £500,000 a week.
Armenia international Mkhitaryan, also 29, will head to the Emirates after he fell out of favour with United manager Jose Mourinho during 18 months at Old Trafford.
Sanchez joined Arsenal for £31.7 million in 2014 after three years at Barcelona but his relationship with the Gunners soured after he tried to orchestrate a move to City last year.
In an Instagram post, he took a parting shot at ex-Arsenal players who have criticised his attitude.
"There are people [former club players] who have spoken with no knowledge of what happens inside the club and cause damage," Sanchez wrote. "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."
Last week, former Arsenal defender Martin Keown called Sanchez "football's biggest mercenary".
In a statement issued by United, Sanchez said he had spent "three-and-a-half wonderful years" at Arsenal "and I bring with me very positive memories of that great club and its fans".
Referring to Old Trafford, he said: "The chance to play in this historic stadium and to work with Jose Mourinho was something I could not turn down.
"I am very proud to be the first Chilean player ever to play for United's first team and I hope I can show our fans all around the world why the club wanted to bring me here."
His move to United was celebrated in his homeland, where fans on social media lauded the Red Devils' "winning" mentality, in contrast to the paucity of recent success at Arsenal.
"The golden destiny of Alexis," said daily newspaper La Tercera.
Mkhitaryan joined United for around £30 million in 2016 after three years at Borussia Dortmund. The highlight of his stay in Manchester was scoring in the Europa League final victory over Ajax last season and he also helped United win the League Cup.
"I would like to wish Henrikh all the success and happiness that I am sure he is going to get. He is a player that we will not forget, especially for his contribution to our Europa League victory," added Mourinho.
Mkhitaryan told the Arsenal website he had "always dreamed of playing for Arsenal".
"Now that I'm here, I'll do my best for this club to create history," he said.
Arsenal boss Wenger said he was happy to acquire Mkhitaryan in the deal.