Ancic, seeded fourth and making his return to tennis this week after a summer swimming injury, hung on against persistent fifth seed Dominik Hrbaty, seeing off the Slovak for a 2-6, 7-6 (7/4), 6-4 victory.

But favourite Ljubicic was upended by eighth-seeded Korean Hyung-taik Lee in a 6-3, 7-6 (7/3) knockout.

The Asian outsider also won the pair's only other match two years ago at the US Open.

The 30-year-old winner came good as he competed in his third quarter-final of the season, moving into a second semi-finals in the Chinese capital.

Lee, standing 60 spots below world No. 3 Ljubicic, established early superiority with a break in the first set which the Croatian could never get back.