Defending champion Lleyton Hewitt admitted he felt powerless to prevent Jo-Wilfred Tsonga from ending his reign at Queen's Club.

Hewitt, a four-times winner at the Artois Championships, was stunned 7-6 (7-5) 7-6 (7-2) by the French qualifier in the biggest upset of this year's tournament.

The Australian sixth seed broke Tsonga to save the second set but was overpowered in the tie break, won by a theatrical smash, to send him tumbling at the first hurdle.

He said: ''I saw a bit of Tsonga's match against Andy Roddick at the Australian Open and he was a set up there and served for the second set, so I knew how flashy he was.

''He kept it up for two sets. Even in the game I broke he didn't really miss too many balls. I had to hit a couple of big returns.

''Even his second serve didn't let me dictate and he came up with some big shots on the lines on big points.''

Tsonga, who returned to action in January after two years out with a back injury, described the victory as the best of his career.

The 22-year-old has now won 30 of his last 31 matches and he said: ''I'm very happy because that's the best result I've had.

''Hewitt is a very good player on grass so it's fantastic to beat him.''

Croatian Marin Cilic, who sent Tim Henman crashing out of Queen's on Tuesday, awaits Tsonga in the third round.

French Open champion Rafael Nadal dispatched Juan Martin del Potro of Argentina 6-4 6-4 on centre court and then insisted he understood Roger Federer's reasons for pulling out of Halle.

Federer, Nadal's victim in Sunday's final at Roland Garros, withdrew from his traditional Wimbledon warm-up, the Gerry Weber Open, citing fatigue.

Fourth seed Novak Djokovic came back from a set down to see off Robert Kendrick of the USA.

Kendrick needed treatment to his left knee after slipping midway through the second set and his movement was affected as a result.

Djokovic, who is ranked fourth in the world, said: "I've been asked if I see myself as a Grand Slam winner and the honest answer is I dream of it.

''My biggest dream is to win Wimbledon because it is the most traditional Grand Slam.''