Aryna Sabalenka stayed on course for her second Grand Slam title of the season after cruising past China's Zheng Qinwen in straight sets to reach the US Open semi-finals on Wednesday. Australian Open champion Sabalenka -- who will take over as world number one next week -- booked her place in the last four with a 6-1, 6-4 victory in 1hr 13min. The Belarusian second seed will face either Marketa Vondrousova of the Czech Republic or Madison Keys of the United States in the last four. "I think I definitely played great tennis today," Sabalenka said, before praising her opponent.