The Black Cats have finally been given permission to talk to the 22-year-old Wigan full-back with the two clubs trying to thrash out a deal.

Keane has been on the England Under-21 international's trail for much of the summer and has had three previous bids rejected by the Latics.

However, PA Sport understands Wigan have now given the Wearsiders the green light to speak to one of their prize assets as they face up to the possibility of losing him.

Sunderland have already invested £16million in new signings so far this summer, and would have to part with around £6million more to get their hands on the Liverpool-born defender.

Wigan boss Chris Hutchings has maintained for much of the close season that the player is not for sale and that he does not want to leave the JJB Stadium in any case.

However, Hutchings' subsequent admission that every player has his price came as Keane refused to give up his pursuit, and now it is down to him to sell his vision at the Stadium of Light to a man who has been linked with a series of Barclays Premier League clubs since establishing himself at Wigan.

The Irishman has so far done that successfully with Greg Halford, Russell Anderson, Michael Chopra, Kieran Richardson and Dickson Etuhu, although did not fare so well with Baines' international team-mate David Nugent.

Last season's Coca-Cola Championship winners withdrew their bid for the then Preston striker as he stalled on giving them an answer with Keane adamant he only wants players who are fully committed to the cause.

Today's development will alert potential competitors to the player's availability, but the Sunderland boss will hope the chance to outline his plans first will prove decisive.

Baines was training with Wigan this morning, but faces a big decision over his future.

Despite investing a total of £10.5million in Chopra and Richardson, Keane continues to work hard on strengthening his defence with Halford and Anderson unlikely to be the only new arrivals.

He has received little encouragement in his pursuit of former Celtic team-mate Bobo Balde, while his interest in £10million-rated Hearts goalkeeper Craig Gordon is ongoing.

Keane and his players headed for a training camp in Portugal yesterday after their 1-0 friendly defeat at Scunthorpe on Saturday.

They will continue their preparations with a tour to Ireland, where they will play against Bohemians, Cork City and Galway after flying out next weekend.