Djokovic keen to overcome crunch moments

World number four Novak Djokovic admits he has to find a way to overcome the nerves that played a key role in his surprise Wimbledon quarter-final defeat against Tommy Haas.

Djokovic was expected to beat the veteran German and reach his second Wimbledon semi-final, but he was outplayed on the crucial points as pressure started to take its toll on the Serb.

Haas, 31, used all his years of experience to close out a 7-5, 7-6 (8/6), 4-6, 6-3 victory that laid bare the psychological flaws in Djokovic's game.

It is not the first time Djokovic has been unable to beat the mental block that sometimes affects him and the former Australian Open champion conceded he will have to find a solution if he wants to win a second Grand Slam.

"I was consistent with my results this year, but I wasn't that successful in the Grand Slams. I didn't make that step further than the quarter-finals," he said.

"I just think that the difference is a little impatience in the important moments. I think I get nervous a little bit more than I used to. And I guess that's probably pressure that I feel. But I shouldn't."

Djokovic was never able to find a consistent rhythm against Haas's superb serve and volley game and grew increasingly frustrated as the match wore on.

The 22-year-old began to shout at his coaches in the players' box and repeatedly slammed his racket into the Court One grass.

His anger stemmed from a disappointing year which has seen the Serb forced to withdraw from an Australian Open quarter-final against Andy Roddick through fatigue and crash out of the French Open in the third round.

"Everybody goes through the crisis," he said. "I've been going through some tough periods at the start of the year but the start of this grasscourt season was all right.

"My game is there. I'm just disappointed now because I thought I was playing well in this moment and I could go all the way.

"But Haas was the better player. If you're playing quarter-finals against a good player like Haas, your time passes by.

"Physically and mentally I was motivated because I wanted to do better in Wimbledon. The quarter-finals is a good result but I still think I can do better.

"I just have to turn the new page and keep on working. I think ups and downs are normal in the career of one professional tennis player."