Juan Martin Del Potro was dumped out of the Rakuten Japan Open as he lost his first-round match 6-4 6-4 against Edouard Roger-Vasselin.

Playing for the first time since claiming his maiden grand slam title in New York, Del Potro was never at his best against world number 189 Roger-Vasselin, who had not previously won a match on tour since last July.

Del Potro, who reached the final in Tokyo last year, told www.atpworldtour.com: "I didn't feel 100%. Everyone could see that.

"I had a little bit of jet-lag and a stomach ache but that's not the reason I lost."

Next up for Roger-Vasselin, whose father Christophe reached the French Open semi-final in 1983, is a second-round clash with Jurgen Melzer of Austria, who beat Argentina's Leonardo Mayer 7-6 (7/4) 6-3.

Elsewhere, eighth seed Lleyton Hewitt was a 6-1 7-5 winner over Japanese wild card Tatsuma Ito.

"My real focus now is the Australian Open next year," said Hewitt. "I am training very hard to get as fit and mentally strong for next season."

Fifth seed Tomas Berdych beat local boy Go Soeda 6-2 6-4.

Two more Frenchmen joined Roger-Vasselin in the second round, with third seed Gilles Simon beating local wild card Takao Suzuki 6-3 6-4 and Fabrice Santoro securing a 6-7 (5/7) 7-6 (7/2) 6-2 win over Andrey Golubev.

The all-German clash between Andreas Beck and Rainer Schuettler was postponed until tomorrow, as was Thomaz Bellucci's match against Mikhail Youzhny,