DOHA — China’s Li Na, who hopes to challenge for a medal at the Beijing Olympics, and Maria Sharapova, who’ll be one of the favorites in the Chinese capital, both stormed into the Qatar Open semifinals yesterday.

Li got the better of her third top 20 victim in a row when she enjoyed a 6-3, 6-4 success against Jelena Jankovic, the world No. 4 from Serbia to add to her wins over Anna Chakvetadze, the fifth-seeded Russian, and Shahar Peer, the 12th seeded Israeli.

The victories have carried Li to the semifinals of this $2.5 million event, the first time she has reached this stage in a tier one tournament. They also continued her great start to 2008 after taking six months off.

Asked why she was playing so well now, Li said: “Maybe because my husband just gave me a credit card — no I’m joking.” Li will now face experienced Russian Vera Zvonereva while Sharapova, who brushed aside Denmark’s Caroline Wozniacki 6-0, 6-1, will tackle Agnieszka Radwanska, the Polish girl who knocked her out of the 2007 US Open.

Li’s success hinged on making the first aggressive hit in the rally and striking the ball more powerfully than Jankovic, forcing her highly rated opponent to contain and defend more often.

However, in the second set it seemed that Jankovic might level things up.

Three times she had Li at 15-30 on her serve, but each time the world number 29 from Wuhan responded with some of her best tennis.

In fact her husband-coach Jiang Shan told her not to worry about how her opponent would play.

Australian Open champion Sharapova maintained her unbeaten record in 2008 as she thundered her way to the semi-finals in less than an hour. The strident brevity of Sharapova’s win over Wozniacki, the promising 17-year-old Dane, suggested she is unofficial favorite for her second title of the year as well provided her with her 12th successive victory in all competitions.

Sharapova now plays Radwanska, the elder of two rising sisters, the first Polish woman ever to make the world’s top 20.

Radwanska achieved her first Grand Slam quarterfinal in Australia last month and has now reached her first WTA Tour semi-final with a three-hour 4-6, 7-6 (7/1), 6-4 win against another 18-year-old, Dominika Cibulkova of Slovakia.

Roddick Avenges Blake’s Loss

to Japanese Teen

In San Jose, California, top seed Andy Roddick blasted seven aces to beat Kei Nishikori 6-2, 6-4 in the second round of the ATP SAP Open, avenging Nishikori’s stunning win over American James Blake last weekend.

The 18-year-old Nishikori shocked Blake, who was ranked 12th in the world at the time, in Sunday’s final at the Delray Beach tournament, becoming the first player from Japan to win an ATP Tour event since Shuzo Matsuoka at Queen’s in June 1992.

But Thursday, American Roddick won four-of-eight break points, ousting Nishikori in an hour and three minutes.

Nishikori managed to win just 54 percent (19-of-35) of first-serve points against Roddick.

The world’s No. 6 player, Roddick barely advanced to the second round, holding on for a 6-3, 6-7 (3/7), 7-6 (7/5) victory over Australian Chris Guccione on Wednesday.

The second-seeded Blake posted a steady 6-3, 6-4 win over compatriot Jesse Levine during their second-round match.

Blake continues to fire on all cylinders at this hardcourt event as he won 28-of-36 first-serve points while saving all five break points he faced, ousting Levine in just over an hour.

Third seed Tommy Haas of Germany did not have the same luck as Blake, as he was upset, 4-6, 7-6 (8/6), 6-3, by American John Isner.

Taiwan’s Lu Yen-hsun and American Mardy Fish also advanced Thursday with victories over American Wayne Odesnik and German Denis Gremelmayr, respectively.

Karlovic, Llodra Reach Rotterdam Semifinal

In Rotterdam, Netherlands, Ivo Karlovic fired a dozen aces while Michael Llodra produced 13 yesterday as the big-hitting pair won into a semifinal showdown at the seed-short ABN-AMRO World Tennis.

Croatian Karlovic defeated German qualifier Mischa Zverev 6-3, 6-1 as the number 24 from Zagreb tries to regain the 2007 form which took him to his first three titles on the ATP.

Llodra kept French hopes pride alive at an event won from 2000- 2002 by his compatriots, putting out the last Dutchman as he beat 20- year-old Robin Haase 7-6 (7-5), 7-6 (7-5).