Cape Town - Defending champion Garbine Muguruza is through to the third round of the China Open following a straight sets win over Yulia Putintseva.
The Spaniard has struggled for form since winning the French Open in July, and she was shaky again at times on Monday.
Muguruza did well to save two break points in the second game before going on to claim successive breaks and take the first set 6-2 - but Putintseva provided a much sterner test in the second set.
Muguruza broke in the first game before taking a 2-0 lead, but her opponent broke back in game four to level at 2-2.
The players then exchanged six consecutive breaks of serve from the seventh game, with Muguruza breaking three times only for Putintseva to break straight back on each occasion.
After spurning two match points in the 12th game before getting broken again, Muguruza had to battle through a tie-break before finally clinching a 6-2, 7-6 (7-5) victory.
"I'm very happy I could close the match in the tie-break because obviously it was getting tougher and tougher. I think she was getting into the match a little bit more," Muguruza said. "I think just tie-breaks are moments where, you know, it's delicate. You only have, like, seven points kind of to win. You feel a bit more nervous and more tense."
Others to reach the third round on Monday included third seed Agnieszka Radwanska, who beat Ekaterina Makarova 6-3, 6-4, and eighth seed Madison Keys, who saw off Kristina Mladenovic 7-5, 6-4.
Top seed and World No 1 Angelique Kerber was also in action on Monday, reaching the second round with a 6-4, 6-4 victory over qualifier Katerina Siniakova, who gave a very solid account of herself despite the scoreline.
Kerber ultimately prevailed, however, securing two breaks to one in each set.
"She played really well, especially in the first set," Kerber said. "I was trying to be patient and waiting for my shots and for my chances, just trying to move her a lot and only going for it when the chance came."