The Chile international completed a move to the Red Devils as part of a swap deal that saw Henrikh Mkhitaryain join the Gunners in the January transfer window.
Sanchez put pen to paper on a contract reported to be worth an eye-watering £350,000 a week to make the South American the best paid player at Old Trafford.
The 29-year-old’s lucrative transfer was the first time that the Chile star had changed clubs in the middle of a season.
Sanchez has only managed to score one goal in 11 appearances in all competitions since his move to the 20-time English champions.
The Manchester United signing opened his account for the Red Devils in a 2-0 win over Huddersfield Town at Old Trafford back in February.
However, Sanchez has admitted that he has found it difficult to swap clubs in January for the first time.
“The change of club was something that was very abrupt – it was the first time I’ve changed clubs in January – but many things have happened in my life that are difficult,” Sanchez is quoted as saying by Sky Sports.
Sanchez moved to Arsenal from FC Barcelona in the 2014 summer transfer window.
The Chilean forward won two FA Cup in three and a half seasons at Arsenal before his move to Manchester United.
The Red Devils will take on Tottenham Hotspur in the FA Cup semi-final.
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