Sania Mirza got off to winning start at the Japan Open

The eighth seed, making her senior debut in Japan, broke Castellvi in the first game and cruised to victory with a succession of angled winners from the back of the court.

"Great," said the 18-year-old from Mumbai. "I played a good match, I got to play two good matches today. I''m hitting the ball good and I like the court. Hopefully, I can continue the way I''m playing."

Mirza started to hit the corners midway through the first set, and although she went off the boil at the beginning of the second, she steadied herself to finish the match in 59 minutes.

"As a tennis player, I''m bound to make a mistake, I''m bound to lose a game, I''m bound to hit some good shots and I''m bound to make some errors, so that's human," said Mirza, who has generated huge media interest in her native country.

"I don''t think anyone expect anyone to play perfect tennis all the time." In the second round, Mirza will take on Japan's Aiko Nakamura, who eliminated 2004 runner-up American Mashona Washington 6-7 (6/8), 6-1, 6-1. It was a long day for Mirza, who also teamed up with Israel's Shahar Peer to beat American doubles pair Jill Craybas and Carly Gullickson 3-6, 6-3, 6-1. Other women's seeds went through safely, although sixth seed Gisela Dulko of Argentina needed three sets to beat qualifier Hsieh Su-wei of Taiwan 2-6, 7-5, 6-2.

Fourth seed Maria Kirilenko of Russia, fresh from her first career title at the China Open two weeks ago, denied 15-year-old Japanese Ayumi Morita on her professional debut with a 6-4, 6-4 win. Top seed Vera Zvonareva of Russia fended off Catalina Castano of Colombia 6-2, 7-6 (7/4), while Japan's Ai Sugiyama, the fifth seed, defeated Alina Jidkova of Russia 6-1, 7-6 (7/5). Three men's seeds -- American Vincent Spadea, the Czech Republic's Ivo Minar and Robin Vik -- fell in the second round.

Eighth seed Spadea bowed to Bjorn Phau of Germany 6-4, 7-5, Minar, the 14th seed, went down to Marcos Baghdatis of Cyprus 6-4, 6-2, while 15th seed Vik crashed to American Kevin Kim 6-2, 6-4.