The Uruguayan was keen to leave the club over the summer, but he ultimately stayed put and has impressed since returning from the suspension which was carried over from last season for biting Chelsea's Branislav Ivanovic.
Werner told the Daily Mirror: "There was interest in him from other clubs throughout the summer but it was important for us to try to keep him.
"He is one of the great players of the world and we felt that we would be a stronger club with him than without him.
"That does not mean I don't respect his intense desire to play in the Champions League. But it would be a very happy day next May if and when we get to the Champions League by finishing in the top four and he is part of it.
"It is our intention to keep him for a while.
"Our intention is to build a winning club and he is integral to that. The past is the past and I have great affection for him personally."
- Sports & Recreation