The 24-year-old, an £8million summer signing from West Ham, has enjoyed a solid first season on Wearside, although at times he has fallen victim to the kind of momentary lapses in concentration which affected older brother Rio during the early days of his career.

At Portsmouth on Monday evening, the Londoner was guilty of a major blunder which allowed John Utaka to force Phil Bardsley to fire into his own net and put Pompey 2-1 ahead within minutes of Kenwyne Jones' opening goal.

The Black Cats went on to lose the game 3-1 and therefore pass up the opportunity to secure their Barclays Premier League status, and as a result they head into Sunday's final-day clash with Chelsea knowing victories for Newcastle and Hull would send them down if they lose.

That would represent disaster for a club which has invested close to £80million in its squad in the last two years with American businessman Ellis Short ready to inject further cash.

Sbragia is acutely aware of the stakes, but is confident Ferdinand will bounce back from his personal disappointment.

He said: "Anton has got enough belief in his game. He has made a mistake, it is as simple as that. But he can rectify it on Sunday.

"We have spoken about it and he understands he made a terrible mistake.

"We all make mistakes in life and unfortunately, he did it on the telly as well."

Sunderland endured mixed fortunes at Fratton Park with Jones having earlier hit the post with a header and Grant Leadbitter inadvertently heading the ball straight into Utaka's path to allow him to equalise, although they were grateful to see Peter Crouch's header also come back off the woodwork at 0-0.

Sbragia admits luck has not always been on the club's side, but has been disappointed that when they have benefited from mistakes by other teams, they have not taken advantage in the same way Pompey did.

He said: "When you are down there, things don't seem to go too right for you.

"When it was 1-1, we had a little spell and maybe a couple of little half-chances before they scored.

"But if we make a mistake like that, we seem to always be punished.

"If it goes the other way, we seem to let teams off the hook, and that's something we need to do better with."

The net result is that Sunderland reach the 38th and last game of the season needing to take something from Guus Hiddink's FA Cup finalists if they are not to rely on the teams below them to ensure their continued presence in the top flight.

A return of just six points from the last 36 on offer has plunged them from the brink of safety back into the thick of the fight for survival, and that is a source of intense frustration.

Asked if he expected them to still be involved in the scramble at the bottom, Sbragia said: "No, not at all.

"We have had many chances to get over that line. We keep talking about it, but unfortunately we haven't taken them.

"Fortunately, the teams underneath us haven't taken the chance either, so it's a case now of going into the last game of the season. We have to go in there and we have to win it.

"That solves any problems of looking at Aston Villa's result (against Newcastle) and looking at Hull City's result."