DICK ADVOCAAT enjoyed a satisfying double on the first day of pre-season training yesterday when a new contract for Lee Cattermole was followed by a second transfer breakthrough.

It emerged last night that Celtic have agreed a fee with the Black Cats for 23-year-old full-back Adam Matthews, suggesting Advocaat has got sick of waiting for Carl Jenkinson to move to the North-East.

Despite agreeing a £2m loan fee with Arsenal for Jenkinson last month, Sunderland have turned their attentions north of the border by bidding for Matthews.

The Wales international is thought to cost in the region of £1.5m and if he does leave it will bring to an end five successful years at Parkhead, where he won the Scottish Premier League four times and faced the likes of Lionel Messi in the Champions League.

He is an attack-minded right-back, who can play left, and has been allowed to leave after Celtic acquired Saidy Janko from Manchester United and he has entered the final 12 months of his contract.

Sunderland have already signed Sebastian Coates from Liverpool and they are interested in Zenit St Petersburg’s Belgium defender Nicolas Lombaerts and Dinamo Kiev’s Dutch forward Jeremain Lens.

The focus is purely on transfers now after agreeing a new contract with inspirational midfielder Cattermole which ties him to Sunderland until 2021.

Agreeing a new deal with Cattermole was regarded as a priority at the end of the season after the player entered the final year of his contract.

And the 27-year-old has been handed a new six-year deal, which is a further five on top of the term he had remaining. Should he see out his latest contract then he will be entitled to a testimonial with the club, having signed in 2009 under Steve Bruce.

An appreciative Advocaat, who has only been at the helm for nine games, said: “Lee is the controller of the side. He is a motivator, a leader and central to the success of our team. To know that he will be with us for many years to come is very important to the club.”

The contract extension is a far cry from at this stage two years ago when he was effectively discarded by former head coach Paolo Di Canio. His frustrations under Di Canio disappeared when Gus Poyet took charge and since then he has been key to Sunderland’s last two successful Premier League survival fights.

Despite interest from Stoke City, who he was on the verge of signing for 17 months ago, Cattermole has pledged his future to the Black Cats.

Sporting director Lee Congerton said: “Lee is a hugely important part of our team, both on and off the field. He has ten years of experience playing in the Premier League, which is incredible when you consider he is still only 27, and we are delighted that he has committed his long-term future to Sunderland.”

Cattermole’s decision to stay followed confirmation last month that Wes Brown had agreed a 12-month extension following Advocaat’s decision to stay. It also arrived just 24 hours after Sunderland announced the £2m, potentially rising to £4m, purchase of Coates.

But Jenkinson is unlikely to be joining. The England Under-21 international would prefer to return to West Ham, where he spent last season. West Ham co-chairman David Gold said: “We are working very hard to get Carl back here.”