The Chile international has been settling into life at Old Trafford after having signed for the Red Devils from Arsenal in the January transfer window.
The 29-year-old has made something of a slow start to life at his new club and he has only scored three goals so far for the Red Devils.
Sanchez is now preparing to come up against his former club for the first time when Arsenal head to Old Trafford to take on Manchester United on Sunday.
Mourinho accepts that Sanchez has not yet hit top gear for the Red Devils but he is expecting to see more from the Chilean next season in a Manchester United shirt.
Speaking at his pre-match news conference on Friday, Mourinho said: “I keep saying I don’t like the January market, but it was now or never, so it was now and obviously if we can have good Alexis until the end of the season, better for us.
“We need seven points, we have a final to play… can he help us the way he’s helping us lately?
“I hope so and I feel so, but what I am sure of is that next season, after pre-season, after being comfortable and adapted, he’s going to be great for us.”
Manchester United are currently in second place in the Premier League table as they look to finish as runners-up to Manchester City in the table.
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