That is the opinion of former Gunners captain Martin Keown.
Alexis Sanchez has struggled to adapt to life in Manchester since joining in January, scoring only four goals in 28 appearances.
The Chilean did score in United’s thrilling 3-2 comeback against Newcastle in October and started the last three games up front, but reportedly wants to quit Old Trafford.
It is claimed the 29-year-old has found it difficult to acclimatise to life outside the bustling London.
Sanchez also does not take well to Mourinho’s tactics and finds it frustrating when the manager praises his tracking back, as opposed to his attacking flair.
Accustomed to a softer approach from Arsene Wenger, the forward is not a fan of Mourinho’s hairdryer treatment, either.
Despite a move to Paris Saint-Germain eyed, Sanchez has impressed in the No 9 role in Romelu Lukaku’s absence.
The Belgian has missed the last three games with a knock and United have produced silkier attacking moves with Sanchez leading a three-pronged forward line.
Keown had a vitriolic relationship with Manchester United during his playing days at Highbury, but believes the club can maximise Sanchez’s qualities by keeping him in the line-up ahead of Lukaku for Sunday’s Manchester Derby.
“While Lukaku does not link well enough, Sanchez gives United really good options,” Keown told the Daily Mail.
He helps them press as a group and gives them an extra zippiness and energy.
“He does not have the same pace as Marcus Rashford and Anthony Martial to accelerate past players in wide positions.
“But when he plays centrally, he can weave things together in a way they can’t.
“Sanchez is a little big man in the way he is so brave and effective in the air.
“When he played in this position for Arsenal, it looked like they had found the perfect No 9.
“Jose Mourinho is trying to get the same from him at United.”