The Chilean is on the verge of completing a move to Old Trafford with Henrikh Mkhitaryan heading to Arsenal as part of the agreement.
United find themselves 12 points behind Manchester City in the Premier League title race with 15 games to go. But rather than simply offering a mid-season boost, Mourinho says Sanchez -- should he sign -- is a player capable of taking United to the next level.
He said: "The team is lacking nothing. It is not the point of lacking something or we desperately need something. It is just thinking about the improvement of the team in the future.
"If it happens, it happens, and we are sure that it is for the good of the future of the team. If it doesn't happen, it doesn't happen."
Mourinho admits doing transfer business in January usually hints that a club has made mistakes in the summer. But the Portuguese coach insists that is not the case with United's pursuit of Sanchez, and that the chance to sign the 29-year-old was too good an opportunity to turn down.give our best, we didn't try our best and we don't like to do it.
"But if you have the chance to do some special players, some player in special circumstances, some player that you do in the summer and you have the chance to do it now.
"That's a special situation and you try to do it. It's as simple as that."
Sources have told ESPN FC that Sanchez is expected to sign a four-and-a-half year deal at Old Trafford once negotiations have been concluded.
