Iga Swiatek drops rare set but reaches French Open quarter-finals

Iga Swiatek beat Zheng Qinwen (Christophe Ena/AP)

Iga Swiatek dropped a set for the first time in more than a month but stayed on course for the French Open title by beating ailing teenager Zheng Qinwen.

There was some doubt that the seemingly unstoppable world number one was going to extend her winning streak to 32 matches when Zheng snatched the first set despite trailing 5-2.