Injured Jo-Wilfried Tsonga crashes out of Japan Open

Former champion Jo-Wilfried Tsonga crashed out of the Japan Open in the second round on Wednesday, ambushed 6-4, 7-6 by Croatia's Ivan Dodig in the tournament's first major upset.

Top seed Juan Martin del Potro thrashed fellow Argentine Carlos Berlocq 6-2, 6-2 to reach the quarter-finals of the $1.43 million event in Tokyo before Tsonga, still feeling his way back from a knee injury, was unceremoniously bundled out.

"I'm not shocked by this result," the second-seeded Frenchman told reporters. "This game is difficult enough with two legs. With one and a half it's complicated."

The world number eight, champion in 2009, retired from the second round at Wimbledon and only returned at Metz a week ago, reaching the final.

He beat fellow Frenchman Gael Monfils in the first round in Tokyo but never got out of the blocks against Dodig.

"I'm still coming back so it's never perfect," said Tsonga, his left knee heavily iced. "It's frustrating but it's part of the job to accept it's going to be difficult when you're not 100 percent. He broke me early and I was always chasing the match."

Dodig's persistence forced Tsonga into a string of wild misses, the end coming when he dumped a forehand into the net to surrender the second-set tiebreak 7-5 and gift-wrap the Croat a second victory in two meetings.

"Hopefully in the next few weeks I will find my legs," added Tsonga. "The doctors said it would take five months for the pain to go away and it's been three months so I have to be careful."

A day after surviving a stern test against Cyprus's Marcos Baghdatis in his first match since a shock second-round exit at last month's US Open, del Potro looked a different player in his first meeting with countryman Berlocq.

He made 70 percent of his first serves and won 86 percent of those points in a 66-minute rout.

But even the statistics fall short of outlining the gulf in class between world number seven del Potro and his 45th-ranked opponent. A kicking second serve which a deflated Berlocq could only flap into the net summed up a thoroughly one-sided affair.

"I played very solid," the 2009 US Open champion told reporters. "I served well, hit my forehand really well and tried to be aggressive. I played much better than yesterday. I felt I was in control of the whole match."

Recovered from his jet-lag following a 37-hour trip from Argentina to Japan, 2008 finalist del Potro next faces Ukrainian Alexandr Dolgopolov, who knocked out eighth seed Janko Tipsarevic of Serbia 6-3, 7-6.

Canada's Milos Raonic, coming off his fifth career title in Bangkok at the weekend, matched del Potro's power in a comfortable 6-4, 7-6 first-round win over local Go Soeda.

The third seed belted 24 aces and whitewashed his wildcard opponent 7-0 in the second-set tiebreak.

"I did a lot of things well and buckled down when I needed to," said the world number 11, runner-up to Japan's Kei Nishikori here last year.