BEIJING – Dinara Safina lost to Chinese wild card Zhang Shuai 7-5, 7-6 (5) in the second round of the China Open on Monday, a result that could lead to Serena Williams taking the No. 1 ranking.

Venus Williams fell to teenager Anastasia Pavlyuchenkova 3-6, 6-1, 6-4, the second time in a week the Russian has beaten her. Novak Djokovic had 10 aces in a 6-3, 7-5 win over Romania’s Victor Hanescu to reach the second round.

Safina would lose her top ranking if she finishes behind No. 2 Serena Williams in this tournament. Williams won her first-round match Saturday against Estonia’s Kaia Kanepi and next faces Russia’s Ekaterina Makarova on Tuesday. Safina can hold the top ranking if Williams loses.

The latest defeat comes a week after Safina was knocked out of the second round of the Toray Pan Pacific Open by 18-year-old qualifier Chang Kai-chen of Taiwan.

“I woke up this morning feeling really excited, but didn’t do any special preparation and never expected to win the match,” said Zhang, ranked 226th.

Safina made 13 double-faults and began shouting and growing distraught toward the end of the match. She did not speak to reporters.

On Tuesday, No. 2 Rafael Nadal and defending champion Andy Roddick begin play in the men’s draw.

Venus Williams got off to a strong start against an 18-year-old opponent who defeated her in the second round in Tokyo last week. Serving for the match, Pavlyuchenkova sent a forehand winner past Williams to wrap up the final set.

“She played really well. Sometimes I just made errors too soon in the point,” said Williams, who totaled 12 double-faults.

“She was playing much better. […] She wanted to kill me I guess,” added Pavlyuchenkova with a smile.