Alexis Sanchez is about to become a Manchester United player

Alexis Sanchez is set to complete his transfer to Manchester United.

Sanchez's move to United from Arsenal is on the verge of been finalised, after Henrikh Mkhitaryan agreed to join Arsenal. BBC journalist David Ornstein broke the news on Saturday evening, reporting that the deal will be a straight swap between the clubs, and no transfer fee will be involved. Mkhitaryan will undergo his medical at some point over the next 48 hours. https://twitter.com/bbcsport_david/status/954816899342323717 Sanchez has reportedly signed a four-and-a-half-year deal - which will keep him at Old Trafford until the end of the 2021/22 Premier League season. The 29-year-old joined Arsenal from Barcelona in 2014 for £31m, he scored 85 goals in 165 appearances for the London club and was part of the team which won two FA Cups. However, it has become increasingly apparent over the past year that he had no intention of extending his stay with the club. He rejected the offer of a new deal and his contract was due to expire at the end of this season. He almost joined Manchester City on deadline day of the transfer window last summer, after Arsenal accepted a £65m bid for the forward. But, as they couldn't secure a replacement, Sanchez stayed and was a frustrated figure at the Emirates. The forward was expected to sign for City this month, but once United entered the race for his signature, and offered a greater financial package, the Premier League leaders ended their interest. Sanchez has reportedly become the fourth-best paid football in the world. Meanwhile, Mkhitaryan has ended his difficult spell with United. The Armenian forward joined the club from Borussia Dortmund in 2016 for £30m. He had been named the Bundesliga Player of Season in his final campaign in Germany, but it soon became clear that he didn't fit into Jose Mourinho's plans. He earned his place in the team last winter, after falling out of favour in the opening months of the season. He also scored in the Europa League final victory over Ajax last May, and started this season in brilliant form, registering five assists in his first four matches. However, the 28-year-old has rarely been used by Mourinho over the past few months. His United career saw him score 13 goals in 63 games.