Bent has not played for Aston Villa since October 27 when he came off the bench against Norwich City.

Only Queens Park Rangers in the English Premier League have scored fewer goals than Lambert's side this season, further highlighting Bent's absence.

That has led to rumours the striker is being denied playing time due to a clause in his contract, allegedly one that would see Aston Villa pay more money to Sunderland if he reaches 50 appearances for the club, but Lambert has claimed his reasons for not selecting the forward are only about football.

Lambert said: "Have there been any enquiries for Bent? No. Has he asked to be put on the transfer list? No. Is there a clause? That's not true.

"I'm not sure where that came from."

Not only has Lambert preferred Christian Benteke as his starting striker, Bent has also missed out on a bench role behind 21-year-old Jordan Bowery.

"I think he (Benteke) has really good manners and he's really humble which is a great thing for a footballer," Lambert said.

"If he keeps that way he will have a massive career.

"He's given us everything he's got and his work ethic is fantastic for us."