Top seed champion Stan Wawrinka muscled into the second round of the Japan Open on Tuesday with a bludgeoning 7-5, 6-3 victory over Czech Radek Stepanek.

French Open champion Wawrinka produced a dazzling performance in the Tokyo sunshine, the Swiss unleashing a series of jaw-dropping backhands that left his opponent shaking his head in disbelief.

"After last year I'm just happy to play well and get through the match," said Wawrinka, who was eliminated by Japan's Tatsuma Ito in the first round last year in a stunning upset and faces the same player in his next match.

"(Ito) is tough to play against, but obviously I'll try to play better than I did last year and hopefully continue to play well all week," added Wawrinka, chasing a fourth title of the year and the 11th of his career.

The spindly Stepanek wore the timid expression of a man hoping to avoid having sand kicked in his face by his hulking opponent, and Wawrinka's one-handed backhand -- one of the most potent weapons in men's tennis -- bullied the Czech into submission.

It effectively settled the first set as he chased down a decent Stepanek volley to whip the ball back past his opponent, breaking his resistance.

He ripped another down the line to break at the start of the second set, celebrating with a roar and a pump of his fist, and thereafter was not seriously threatened.

Wawrinka, who made his grand slam breakthrough at last year's Australian Open after years spent in the shadow of countryman Roger Federer, delivered the coup de grace with his 11th ace to wrap up only his second win over Stepanek in six meetings.

Wawrinka's quest for a first Tokyo title promises to be a difficult one, with defending champion Kei Nishikori arguably a slight favourite to capture his third Japan Open on a court he has owned in recent years.

Meanwhile, Australians Bernard Tomic and Sam Groth both retired after dropping the first sets in their respective first-round matches.

The controversial Tomic, who earlier this year launched a tirade against Australian tennis officials for a perceived "lack of respect" towards him, blamed sickness for throwing in the towel against American Steve Johnson while losing 6-3, 2-1.

Groth sprained his right ankle while trailing Frenchman Jeremy Chardy 6-3, 2-0.

In other matches, Luxembourg's Gilles Muller upset fifth seed Kevin Anderson of South Africa 6-2, 6-3, while Cyprus's former Australian Open finalist Marcos Baghdatis beat Spaniard Fernando Verdasco 7-5, 6-1.
Source: AFP