Manchester United have signed Chile forward Alexis Sanchez from Arsenal in a deal that sees midfielder Henrikh Mkhitaryan move to the London club, the Premier League clubs said on Monday. The 29-year-old Sanchez, who was out of contract at Arsenal at the end of the season, has joined the Old Trafford club after local rivals Manchester City had pulled out of the running. Sanchez said: \u201cI am thrilled to be joining the biggest club in the world. 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\u2019s first team and I hope I can show our fans all around the world why the club wanted to bring me here." Sanchez missed Arsenal's 4-1 win over Crystal Palace on Saturday to have a medical in Manchester on Sunday. He would have been available on a free transfer when his contract expired in four months' time but once City baulked at the amount of money involved in a mid-season deal, United manager Jose Mourinho urged his club to step in. Also Watch: \u201cAlexis is one of the best attacking players in the world and he will complete our very young and talented group of attacking players," said Mourinho. "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's dimension and prestige." Sanchez almost joined City at the end of the August transfer window but that deal fell through as Arsenal could not sign a replacement. He scored 80 goals in 166 appearances after the London club paid 35 million pounds ($48.83 million) for him in July 2014, and won the FA Cup in 2015 and 2017, scoring in both finals. Missing out on the Champions League this season was a bitter disappointment, however, followed by another blow when Chile failed to qualify for this year's World Cup finals. A move to either of the Manchester clubs became a preferable option to signing a new contract. Arsenal wanted Mkhitaryan in exchange and the Armenian has joined on a long-term contract.