SAM ALLARDYCE thinks Sunderland’s players still have time to prove Dick Advocaat wrong for admitting defeat in his attempts to keep Premier League football at the Stadium of Light – even though he is yet to crack the team’s failings himself.

Advocaat quit as the Black Cats’ head coach in October after effectively admitting the task of keeping them up was greater than he thought when he agreed to stay on last summer.

Allardyce set his stall out on his first day in the job to prove the Dutchman wrong, and accepts his transfer business last month suggested his predecessor’s assessment of the squad was right.

But having drafted in Wahbi Khazri, Dame N’Doye, Lamine Kone, Jan Kirchhoff and Steve Harper during his first transfer window, Allardyce thinks the longer serving members of the squad still have an opportunity to unite to achieve another escape act.

"I suppose my honest answer would have to be if I thought we were good enough I wouldn't have entered the market,” said Allardyce. “I entered the market because I felt we had to get better than what we were.

“Hopefully, hopefully, those players will make us better - and I think make the rest of the players better. When they see new players coming and doing well and like the look of them, the players can say 'well we are a better squad, we can achieve a bit more.'”

Despite Allardyce’s efforts to make Sunderland a tighter unit, his team have not kept a clean sheet since November 28 when Stoke City left the North-East nursing a 2-0 defeat.

That stretches to12 games, including the FA Cup defeat at Arsenal, and such a poor defensive record has frustrated Allardyce even though he has been encouraged by aspects of his team’s recent displays.

"I've not done my job yet - we won't know until we find out at the end of the season how good I have been,” said Allardyce. “If we continue to try to build on what we've got and try to achieve with the new players - it's been a big relief to me that they've shown they've got some real talent even as early as this coming from abroad and hopefully they can continue to show that talent - hopefully that can help us achieve more results.”

He added: “I think we have failed in defence more than anywhere else. We've conceded too many goals and not got enough clean sheets in that department. The one thing I wanted them to do above anything else was to keep more clean sheets.

“We haven't kept one for more than ten. From my point of view it's the biggest failure. If we'd had four clean sheets in the last nine we'd be out of the bottom three.”

This afternoon, after running both Manchester City and Liverpool close, Sunderland will attempt to address that slump by defeating Manchester United when the spotlight will be on Louis van Gaal once more.

United are up to fifth following a recent improvement in form but remain six points shy of a Champions League spot and criticism of the team’s style of play under the Dutchman remains strong.

It has led to speculation that Jose Mourinho has already been lined up to replace van Gaal at the end of the season.

"The results of van Gaal’s conversations with Man United’s owners are the most critically important thing in determining how it goes forward. Louis' a different case (to me) I knew I was going (from West Ham last year).

“It was me as much as my club not renewing my contract. At first the only person I told was my wife. But with the speculation about the new manager growing it seemed David (Gold) was looking for a new manager anyway so in terms of our timing it all became right anyway.

"But once you don't have the results you want speculation is rife. The only way you overcome it is doing what Louis' doing now - that's his team winning football matches.”

Had van Gaal under-achieved? Allardyce said: "Have I under-achieved since I've been here... what have I done? I haven't got us out of trouble yet. Could I have done more? Maybe.

“I think everybody, as a manager, tries to get the best out of their players. If the players don't do what's expected of them you do what I did, you move in the transfer market.

“I was hoping to get more results than I got from the players in my time here up to the window. Since the window I've got four in. Louis won't have done as well as he would have wanted but there's been a massive problem for us all.

“It is how many injuries do you get? If you get too many injuries which they've suffered from, which Liverpool have suffered from, particularly, then those consistent performances become more difficult to get. So under-achieved? I think the players have under-achieved not Louis van Gaal."