Top seed Serena Williams stumbled her way into the third round of the China Open on Tuesday while men's favourites Novak Djokovic and Rafael Nadal powered through their opening matches.
The world number one Williams at times appeared agitated during her 6-4, 7-5 victory over Italian Francesca Schiavone, 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 Williams 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 ranting and Schiavone smashing balls into the barriers at the side of the court in Beijing.
But Williams seemed calmer - and quieter - as she closed in on a hard-earned 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 said.
Her sister Venus meanwhile crashed out 6-1, 6-2 to Wimbledon finalist Sabine Lisicki. The 12th seed Carla Suarez Navarro defeated American Lauren Davis 6-4, 6-2 to book her place in the third round.
On the men's side, Djokovic signalled his intent to reclaim the title he won in the Chinese capital last year, sweeping aside Lukas Rosol 6-0, 6-3.
The Serbian world number one - and top seed - dumped out his Czech challenger in just 53 minutes.
Nadal, who could unseat Djokovic in the world rankings after Beijing, faced slightly more resistance from Santiago Giraldo, with the Spaniard claiming a 6-2, 6-4 win in about 90 minutes.
The second seed will now face German Philipp Kohlschreiber, while Djokovic will meet Spain's Fernando Verdasco in the second round.
Fifth seed Richard Gasquet and sixth seed Stanislas Wawrinka both safely negotiated their way through.
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.
Verdasco claimed victory over Somdev Devvarman of India 7-6 (8/6), 6-3 and American Sam Querrey defeated Mikhail Youzhny of Russia 7-6 (7/3), 6-3.