Mourinho said: “We have got one of the best attacking players in the world and he's very important for us because we want the best possible players.
“He can play everywhere, in the attacking positions.
“I know him for many, many years, I was with him in Italy when he was at Udinese and I was at Inter.
“In Spain, when he was at Barcelona, in England when he was at Arsenal... so our careers are almost made in the same countries simultaneously, so I know him very very well.
The best moments from Alexis Sanchez playing for Arsenal in the Premier League
“I have seen him play on the right, on the left, as a striker and behind the striker; these are Alexis' positions.
“I have seen him play different tactical positions, different philosophies. I have seen him be successful in every country with every manager and every position.
“So he's a player that becomes more than a player because of that motivation; he can play in four different positions.”