China’s top player Li Na breezed past Romania’s Sorana Cirstea in straight sets on Friday to ensure a place in the Australian Open’s fourth round. The sixth seed, a finalist at Melbourne Park in 2011, won 6-4, 6-1 in 71 minutes and will next play 18th-seeded German Julia Goerges, who beat Li’s compatriot Zheng Jie in their third round clash. But it wasn’t plain sailing for Li in a seesawing first set, with the Chinese number one making a slew of unforced errors and double faults in throwing away two service games. Li got an early break against her 27th ranked opponent to go 2-1 ahead and was cruising at 4-1 before she was broken to put the pressure on. The 30-year-old from Wuhan, a former French Open winner, responded by stepping up to break again but her service game let her down once again before she cut down the error rate to take the set. It broke the Romanian’s spirit and she crumbled in the second set, with Li racing through it in just 28 minutes to stay on track for a potential quarter-final showdown with in-form fourth seed Agnieszka Radwanska.