Serena Williams withdrew from her quarterfinal match at the Italian Open on Friday due to a back problem, and older sister Venus was beaten by defending champion Jelena Jankovic. Jankovic's semifinal opponent will be second-seeded Maria Sharapova, who rallied past 2005 runner-up Patty Schnyder 6-7 (3), 7-5, 6-2 for the 300th win of her career. Sharapova will become No. 1 in the rankings Monday, courtesy of Justine Henin's retirement. Serena's back stiffened suddenly while warming up on a practice court for her match with French qualifier Alize Cornet, who will meet sixth-seeded Anna Chakvetadze, a 6-2, 3-6, 6-1 winner over Bulgarian qualifier Tsvetana Pironkova. “It just happened all of a sudden in practice,” Serena said before heading to a hospital for medical tests. “I just went for a shot and then my back got a little stuck.” Serena did not appear in much pain, carrying a large pocketbook over her left shoulder as she entered a news conference immediately after her withdrawal. “I didn't feel anything the last match, and I don't expect this to cause any problems with my preparation for the French,” she said. “It just happened all of a sudden. I feel like I'm going to be good going into Roland Garros.” This tournament is an important clay-court tuneup for the French Open, which begins May 25. Sharapova required 2 hours, 44 minutes to dispose of Schnyder, and improved to 7-1 in her career against the Swiss lefty. “This is just practice for the French, and I want to play a lot, but I've got to be careful with what I wish for because I'm having a lot of court time,” Sharapova said. Jankovic beat Venus Williams 5-7, 6-2, 6-3, with the American committing 57 unforced errors to the Serb's 24. The Williams sisters haven't met in a final since Serena beat Venus for the 2003 Wimbledon title. Nadal to play Djokovic Rafael Nadal will play Novak Djokovic for the No. 2 ranking in tennis when they meet in the Hamburg Masters semifinals. Nadal has been ranked second for a record 147 consecutive weeks, but he will be overtaken by Djokovic if the Australian Open champion wins Saturday's showdown. Roger Federer won't have such problems. His No. 1 slot is not under threat - yet - and the defending champion plays unseeded Andreas Seppi in the other semifinal. Federer is seeking his fifth title in Hamburg. The top three players in the world all advanced in straight sets from Friday's quarterfinals. Neither has lost a set so far. Federer cruised past Fernando Verdasco 6-3, 6-3; Djokovic beat Albert Montanes 6-2, 6-3; Nadal, last year's runner-up, topped his mentor and friend, the 11th-seeded Carlos Moya, 6-1, 6-3. Seppi reached his first semifinal of the year by beating Nicolas Kiefer 6-3, 5-7, 7-5. Nadal would have been replaced as No. 2 already Friday, had he lost to Moya. But the younger of the two Spaniards came through under pressure and rolled past Moya, losing his serve only once in the match. “It may be a little more important than a normal Masters Series semifinal, but it's not very special. It's not for No. 1,” Nadal said.
