Belgium’s Kim Clijsters returns a shot to Chanda Rubin of the US in Los Angeles on Thursday. (AP)

Los Angeles: Justine Henin-Hardenne clawed her way to a three-set victory over Anastasia Myskina in her opening match of the WTA tour championships as arch-rival Kim Clijsters booked a semi-final berth with her second straight-set win here Thursday.

Henin-Hardenne, who arrived in Los Angeles nursing a cold and sinus infection, dropped the first five games of the opening set to Myskina, then reeled off seven games with the aid of on-court medical treatment.

“I was having trouble breathing because of the cold I’ve had the last few days,” she said. “I was short of breath. I explained it to the doctors.

Myskina said the injury time-out didn’t distract her.

“It didn’t affect me,” she said. “It was my mistake. I let her play better. It was my fault.”

Myskina came out ahead at the end of a see-saw second set, breaking Henin-Hardenne in the 12th game after they had twice traded breaks.

Leading 5-4 in the third, Myskina pushed Henin-Hardenne to 0-30 on the Belgian’s serve, but couldn’t earn the winning break.

Instead, Henin-Hardenne earned the decisive break in the 11th game as Myskina double-faulted to give her break point then netted a forehand.

The Belgian served out with a love game to wrap up the match after two-and-a-half hours.

“I came through, that’s the most important thing today,” Henin-Hardenne said. “It’s an important victory.”

If she makes the semis, she will lock up the season-ending No. 1 ranking.

Meanwhile, current world No. 1 Clijsters booked her place in the last-four with a 6-4, 6-4 victory over Chanda Rubin. “It’s nice,” Clijsters said. “I’ve played two good matches. To be the first one, it’s a relief I think, as well.”

Clijsters led 4-1 and then 5-2 in the first set, but couldn’t capitalise on her six set points in the eighth game as Rubin fought back to narrow the gap to 5-4.

Clijsters converted her seventh set point when Rubin missed a backhand volley.

“When I had to do it, I did it,” Clijsters said. “That’s the most important thing — to be strongest at the moment when you have to be. I was up two breaks,” she added. “And it’s very unusual to lose a match when you’re up two breaks. Even when she broke to go to 5-4, I still had to serve for it.”

Rubin could not find a way through in the second set, failing to earn a break point.

Clijsters broke her to love with a perfectly placed lob to lead 4-3, held her own serve to love in the next game and — after Rubin held serve — took the match with another love game.

Rubin’s defeat, coupled with her opening win over Amelie Mauresmo on Wednesday, left her vying with the Frenchwoman for the second semi-final spot from the Red Group.

Mauresmo must beat Clijsters in her final round-robin match.

Rubin will face Dementieva when round-robin play wraps up Saturday.

(Reuters)