Breaks were traded both early and late on during the opening set, which in turn forced it into a tie-breaker. That was just as close, but Poland's Radwanska eventually edged through 7-5.
It appeared that the world number four was going to ease into the semi-finals when she broke early in the second set, but her Chinese opponent responded with two breaks of her own to force the match into a decider.
Radwanska recovered from that setback, though, and either side of a rain delay she recorded a double-break to leave herself just one game away from the win. She then went on to seal the victory with what was her eighth match point.
The 24-year-old will now take on Sabine Lisicki for a place in the final.