Jelena Jankovic booked her semifinal berth at the $600 000 WTA hardcourt tournament in Los Angeles on Friday, continuing her progress toward the world number one ranking.

The top-seeded Serb, who can overtake countrywoman Ana Ivanovic atop the WTA world rankings by lifting the trophy in LA, passed her toughest test so far this week with a 7-5, 6-4 victory over ninth-seeded Russian Nadia Petrova.

Although Petrova had lost four of six prior career meetings with Jankovic, she was runner-up to Ivanovic last year on the courts of the Home Depot Center in the Los Angeles suburb of Carson.

While Jankovic doesn't have to contend this week with Ivanovic, who didn't return to defend her title, Jankovic has been dealing with a nagging knee injury she suffered at Wimbledon.

In the semifinals, the 23-year-old will face fourth-seeded Russian Dinara Safina, who beat eighth seed Victoria Azarenka of Belarus 6-3, 6-1.

Safina, ranked ninth in the world, is enjoying a breakout season, with a triumph in Berlin and a run to the French Open final, where she lost to Ivanovic.

Also a finalist recently at 's-Hertogenbosch, the 22-year-old Safina now is 20-3 since the start of May and has beaten the likes of former number one Justine Henin, Maria Sharapova and Serena Williams in that span.

Azarenka, 18, has yet to win a WTA singles title, but has reached two finals this year and ascended to a career-high ranking of 16th prior to her loss on Friday.

With second-seeded Williams joining elder sister Venus and Lindsay Davenport as top Americans pulling out of this event because of injury, fans were pinning their hopes on wild card Bethanie Mattek.

Mattek ousted Czech Nicole Vaidisova en route to the quarterfinals, and reached the semifinals with a 6-2, 7-5 victory over China's Yuan Meng.

Mattek moved within one victory of reaching her first WTA Tour final.

She'll have to get past Italian veteran Flavia Pennetta in the semis. Pennetta defeated Austrian Sybille Bammer 7-6 (7/3), 3-6, 6-1 in the quarterfinals.

Pennetta, 26, improved to 32-13 for the year, which has included titles in Vina del Mar and Acapulco.

AFP