The Russian top seed, who hit 17 double faults in three sets Thursday, committed another 14 double faults before finally seeing off Sugiyama 4-6, 6-0, 6-1.

In the semifinals Saturday, Sharapova will take on fifth seed Ana Ivanovic of Serbia, who eliminated her compatriot and fourth seed Jelena Jankovic 3-6, 6-4, 6-2.

The other semi will be a re-match of last year's final between Swiss former world number one Martina Hingis and defending champion Elena Dementieva of Russia.

"I felt worried about my serve too much in the first set. That was the reason for me not being aggressive enough. Obviously some part of my game was off and in this tournament it's my serve," said Sharapova.

"But I thought I did a good job just focusing on what I have to do, even if I gave her many free points off my serve.

"I played enough matches in the last couple of weeks. Getting into a Grand Slam final (at the Australian Open) definitely gave me some confidence," added the US Open champion.

The 19-year-old Russian, the winner here in 2005, failed to keep a service break up in the beginning as she hit her third double fault on a break point to be pegged back at 3-3.

She hit another double fault to go to deuce in the 10th game, allowing Sugiyama eventually to take the set with an excellent backhand down the line.

But that turned out to be Sugiyama's best moment as Sharapova dominated the rest of the 87-minute match.

Meanwhile second-seeded Hingis, seeking a record fifth title here, needed only 42 minutes to beat Samantha Stosur of Australia 6-0, 6-1, while third seed Dementieva whipped Italy's Roberta Vinci 6-1, 6-2.

"I just love the whole idea of being here in Japan and Tokyo and being relaxed. Today it just seems that everything was on my way. I was able to focus, except the three double faults," Hingis said.

"If I play the way I played today, I don't have to really be afraid of anybody who is on the other side," she added.

"Last year in the final she (Dementieva) played just too good. I'll be definitely looking forward to play her again. We'll se what will happen this year."