The midfielder only joined the Latics last summer for £3.5million from Middlesbrough and enjoyed an impressive debut campaign at the DW Stadium.
Roberto Martinez: "I am not worried about the situation with Lee, as he is still a young man and you want that interest.
"I want the top clubs in world football to be talking about our players and about our football club.
"I prefer that to people not talking about our players. That is always a bad sign.
"It is down to us to keep progressing and making sure we are allowing these players to remain motivated and have the incentive to continue progressing. That should be part of our growth as a club and we need players like Lee around to do that.
"It is important that Lee has his targets and keeps developing as a player, and we hope he can fulfil his potential.
"We have all seen he is a leader and someone who can go to the very top in world football. To have a player like that at your club is very exciting."