Lambert has claimed that he is not surprised by the transfer gossip, but does not expect his goalkeeper to lose focus.
"I only heard about the story this morning and that Jack had quashed the rumours," The Sentinel quotes the manager as saying. "Butland is one of the best goalkeepers going around, in Europe terms as well. Without a doubt the boy's a terrific goalkeeper, a good lad as well.
"Does it surprise me that rumours fly about? Not really, because rumours fly about all good players and he's one of the best. He's too good a guy, too good a pro to be affected by any talk. He's been terrific since I've been here and as a person he's been great too."
Butland has kept just four clean sheets in 25 appearances for Stoke this season.