Roy Keane has admitted the next few weeks could be vital for the future of Sunderland as he attempts to push home his summer transfer plans.It emerged on Thursday that the Black Cats had table a series of bids - understood to amount to around £16million in total - for Tottenham quartet Steed Malbranque, Pascal Chimbonda, Younes Kaboul and Teemu Tainio.

Keane, who revealed on Thursday he is yet to sit down with a single transfer target to attempt to sell the club to them, was awaiting developments as he jetted off with his current crop of players on a pre-season trip to Portugal.

However, whatever happens over the next 48 hours or so, the Irishman knows the weeks before the new Premier League season gets underway are crucial.

He said: "The first year at the club, I said getting promoted, I honestly felt, was easy.

"I thought last year was very important, but this summer, the next two or three weeks is a vital part for Sunderland, for the club's future and my future.

"That's why it's vital the squad gets the improvement we need. Since we kicked a ball at the end of the last season, we have lost three players for us, Kenwyne (Jones), (loan signing) Jonny (Evans) and Paul (McShane) - and we were short last year.

"We were short in terms of the squad, so we are three down - and this year, you need seven subs. We will just about manage that, I think.

"It is an important few weeks for the football club for the future, without a shadow of a doubt."

The extent of Jones' knee ligament injury will become clearer when he visits his surgeon within the next three weeks, but he is likely to miss at least the first two months of the season.

Keane has pursued a series of strikers this summer, during which he has been linked with Spurs' Darren Bent, Everton's Andrew Johnson and Manchester United's Louis Saha.

But with McShane out after undergoing surgery to repair a fractured kneecap and Evans back at Old Trafford, efforts to strengthen at the back are equally pressing.

French full-back Chimbonda, who has also been heavily linked with Everton, and Kaboul, who joined Tottenham in a £7million move from Auxerre last summer, would fit the bill.

Malbranque and Tainio would add strength to a midfield which at times last season, included strikers Michael Chopra and Daryl Murphy playing out of position.

Keane has admitted he has not got the £50million to spend which had been suggested would be at his disposal this summer, but is still determined to significantly improve a squad which managed to finish 15th last season.

He said: "We want to do better and I believe we will if we get decent players.

"But it is obviously going to be tough having lost Kenwyne, Jonny and Paul."

The Black Cats face Sporting Lisbon on the Algarve on Sunday evening in their first warm-up game, and then take on Vitoria de Setubal on Wednesday.

However, the manager will only be concerned with results once the new league campaign kicks off against Liverpool next month.

Keane said: "Let's not get bogged down by pre-season in terms of the games we have got against some good opposition.

"All that will go out of the window when we play Liverpool, and I still believe no matter what games we play in pre-season, you don't really get your match fitness until you have played, four, five, six games in the Premier League."

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