STEVE Caldwell has admitted Sunderland are struggling to cope with their inability to turn positive performances into points.

While the centre-back insisted the spirit in the Black Cats' camp remains positive, a return of just one league win this campaign was proving hard to take.

The Sunderland players have been praised for their battling performances during the season, epitomised by their last two top-flight games against Manchester United and Newcastle United. But despite playing well their return is a mere five points from ten games.

"It's difficult to take just now because we are playing well and we are the better team in a lot of games and we are losing," said the Scotland international, who captained the side in their 3-0 defeat at the hands of Arsenal on Tuesday.

"It's a problem because there's no point in us keep saying 'we played well but we keep losing' because we know we have to win games.

"We're trying to win every game and after analysing it a bit and trying to stop the mistakes we make we just move on to the next game.

"We see Saturday as a winnable game. We would have said it in July and we're still saying it now. We have to win - we're looking forward to it and if we play like we played against Newcastle I'm certain we'll win."

Despite the disappointing start, the 25-year-old says the team spirit is strong, if different, from last season, with the players firmly focused on picking up three points at home to Portsmouth on Saturday.

"It's (team spirit) slightly different this season - you always get that when you've got new players in the squad," said the former Newcastle United player. "It's nothing to do with there being a lesser spirit, it's just different.

"I don't know why that is but it's not a problem - we all get on well. It's not a nice thing losing and drawing games and being down near the bottom."

Caldwell admitted the Carling Cup defeat at the hands of the Gunners was desperately disappointing, labelling it the club's worst performance of the season.

What made it even more difficult to take was that in came in from of a near sell-out crowd of more than 47,000 at the Stadium of Light.

"It's disappointing losing any game because you get into that sort of habit and it's something we don't want because we've played well recently," said Caldwell.

"It was great (to play in front of big crowd). We've played with two fantastic atmospheres in the last two games.

"Sunday was something special - a game we should have won never mind got a draw from - we were by far the better team in the second half.

"We didn't just turn up (against Arsenal) because our objective is to win every game we play in but our main objective is to stay in the Premier League and we'll be back ready for Saturday."

* Robin van Persie has proved to Arsene Wenger he is back to his best following a troubled start to the season - but the Dutch youngster could still find himself on the sidelines for the derby clash against Tottenham at the weekend.

The 22-year-old Holland international scored twice against Sunderland in a 3-0 Carling Cup win but Wenger has Jose Antonio Reyes returning from a rib injury and the Gunners will also have club record scorer Thierry Henry available.

Van Persie has not started a Barclays Premiership game since the goalless draw against West Ham in September and could be on the bench again with Dennis Bergkamp also in contention to start the north-London derby.

''There is a lot of competition up front,'' Wenger said. ''We have Reyes coming back, (Freddie) Ljungberg coming back.''

However, the brace at the Stadium of Light proved Van Persie is back on form. The youngster endured a troubled few months, having been kept in jail for two weeks this summer while under investigation after a rape allegation he denies.

Van Persie was also criticised for a wild tackle against FC Thun in the Champions League, which led to a red card and questions of his temperament following a similar dismissal against Southampton last season. But Wenger was impressed with how Van Persie has overcome the difficulties.

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