Emery hails 'very good player' Sanchez.
Unai Emery has revealed he was eager to sign Alexis Sanchez from Arsenal while he was Paris Saint-Germain boss.
The Chile international is making his Emirates Stadium return for the first time tonight since he left the Gunners to join Manchester United last year January.
However, when Emery was asked if he tried to sign the 30-year-old, who moved to Old Trafford in an exchange deal with Henrikh Mkhitaryan, he replied: "Yes. He is a very good player and, when I was at PSG, we thought he could help him.
"We spoke about a lot of players, about a lot of important players, and one was the possibility of Alexis. But it was not possible."
The Spaniard added: "I respect him. In my preparations, every player is (prepared in) playing against the best players from Manchester United and one is Alexis Sanchez.
"I don't know why his performances or quality is better or worse in these circumstances. Now, in the last matches, they are playing very, very well with very big performances.
"He's been starting on the bench after an injury, but, if he plays Friday, we need to work to stop him because he is a very good player."