JOHN O’SHEA admits Sunderland’s ongoing relegation battle is the toughest fight of his footballing career, and concedes the Black Cats are destined for League One unless they address the defensive failings that proved their undoing in Tuesday’s 3-0 defeat to Aston Villa.

O’Shea is a veteran of countless successful survival pushes during his six-and-a-half year spell at the Stadium of Light, the vast majority of which were achieved against the odds, but even he has to concede that the club’s current position, four points adrift of safety at the foot of the Championship table, is dire.

Sunderland have just ten more matches in which to dig themselves out of trouble, with another game having been crossed off the list after they were comprehensively beaten by Villa.

Having shown signs of improvement in their draws with Middlesbrough and Millwall, the Black Cats flat-lined as they were contemptuously brushed aside two days ago, with their inability to defend their own penalty area once again proving their undoing.

Lewis Grabban was left completely unmarked as he scored on his return to the Stadium of Light, and Sunderland’s defence went AWOL again on the stroke of half-time as James Chester doubled Villa’s lead.

O’Shea was partly to blame for the first goal, failing to cut out Albert Adomah’s delivery as he crossed from the left, and the Sunderland skipper admits relegation will be unavoidable unless there are immediate defensive improvements.

“Is it the toughest challenge? Potentially, yeah,” said the 36-year-old centre-half. “But we still have a chance. There’s still 30 points to play for and we’re still in the fight, but we have to stand up and be in that fight properly.

“You can’t keep hoping teams lose if you keep losing because the games are going to run out. You have to somehow dig that result out, that three points, that clean sheet. If we do that, we'll give ourselves some chance.

“We don’t want to be where we are, but we are, and we have to face that quickly and find the momentum, digging it out together somehow from somewhere.

“Whatever team is selected, whatever team is fit and available, we have to do that, and if we do, we'll give ourselves some chance. Until we do that, it's not looking good at the moment.”

Chris Coleman pointed to his players’ mentality as their major failing in the wake of Tuesday’s defeat, and O’Shea agrees with his manager’s assessment of the squad’s ongoing struggles.

Sunderland boast plenty of players with ability – O’Shea, Lamine Kone and Lee Cattermole were regulars at Premier League level, while the likes of Bryan Oviedo, Callum McManaman, Aiden McGeady and Jonny Williams all boast plenty of appearances for top-flight clubs – but confidence is clearly at rock-bottom and the first sign of a setback can often result in a complete collapse.

Tuesday’s game followed a familiar script, with Sunderland conceding a second goal on the stroke of half-time to effectively end the contest, and while the Wearsiders actually boast a decent record whenever they have claimed the lead this season, their attempts to deal with going behind have generally been abject.

That will have to change in the final ten matches, with mental strength likely to prove every bit as important as technical ability.

“It’s the mentality of every individual, looking at yourself first and foremost, making sure you’re doing everything right,” said O’Shea. “Then you should be looking at your mate alongside you to make sure he's doing everything right.

“When you combine that together, that's when the team unit comes together – defensive unit, midfield unit, attacking unit, whatever.

“It’s the basics, everyone together. Mistakes will happen, but you need to do the basics well – stopping crosses, defending crosses, marking men in the box, getting decisions right, all those basics. If you do that, you get clean sheets and you give yourself a chance to win games.

“You couldn't say Aston Villa were incredibly better than us, but we're giving teams too much of a helping hand, and that's the truth of it. Until we get back to keeping clean sheets, we've got no chance because we can't expect to be scoring two, three, four goals in a game to get wins.”

O’Shea only played in the opening 45 minutes of Tuesday’s game, with a thigh injury preventing him from appearing in the second half.

The Irishman was in obvious discomfort for much of his time on the field, and might well have come off sooner has Tyias Browning not suffered a knee injury that curtailed his own involvement.

Browning is unlikely to feature in Saturday’s game at QPR, and with Jake Clarke-Salter serving the final game of his three-match suspension, Kone will be the only available centre-half if O’Shea fails to recover in time.

“We'll have to wait and see,” he said. “I was seeing if I could run it off and the next thing Tyias goes down so it was just one of those things. It's sore at the minute, but fingers crossed I'll have a chance for Saturday.”