Serena stumbles through into third round of China Open

Serena Williams stumbled her way through to the third round of the China Open Tuesday, claiming victory over Francesca Schiavone in an unconvincing two sets.

The world number one at times appeared agitated during her 6-4, 7-5 victory over the Italian, shouting at herself over lost points.

The American only showed rare moments of her trademark power-play, gaining the upper hand in the first set via a mistake from her opponent who double-faulted on set-point.

The top seed was forced to become more aggressive in the second set after her serve was broken in the first game by Schiavone, Italy's first Grand Slam winner at Roland Garros in 2010 and the current world number 50.

As the competition intensified both players' tempers threatened to boil over, with Williams shouting and Schiavone smashing balls into the barriers at the side of the court.

But Williams seemed calmer -- and quieter -- as she closed in on victory.

"I was able to save some energy, so I started walking slower and taking my time more. When I did that, I actually won three or four games in a row," she told reporters after the match.

The 32-year-old and her sister Venus suffered a disappointing first-round exit in the doubles competition on Monday against Taiwan's Chan Hao-Ching and American Liezel Huber.

Serena smashed her tennis racket furiously into the ground when the pair lost the game as she double-faulted at match-point.

Elsewhere on Tuesday, 12th seed Spaniard Carla Suarez Navarro defeated American Lauren Davis 6-4, 6-2 to book her place in the third round of the women's singles competition.

In the men's singles, fifth seed Richard Gasquet and sixth seed Stanislas Wawrinka both safely negotiated a passage through to the second round.

France's Gasquet defeated Florian Mayer of Germany 6-3, 7-6(7/2), while Switzerland's Wawrinka needed three sets to overcome Italian Andreas Seppi 4-6, 6-3, 6-4.

The other early session matches saw Spain's Fernando Verdasco claim victory over Somdev Devvarman of India 7-6(8/6), 6-3, and American Sam Querrey defeat Mikhail Youzhny of Russia 7-6(7-3), 6-3.