Caroline Wozniacki maintained the momentum she built at the US Open by beating last year's runner-up Belinda Bencic in the first round of the Pan Pacific Open on Tuesday.
The former world number one produced her best run at a grand slam for two years by reaching the semi-finals at Flushing Meadows this month, missing out on the final when she was beaten by eventual champion Angelique Kerber.
Wozniacki was back in action for the first time since her exploits in New York on day two of the WTA Premier tournament in Tokyo and ousted Bencic with a 6-2 5-7 6-1 victory.
Swiss Bencic, beaten by Agnieszka Radwanska in the final 12 months ago, was broken eight times as 2010 Pan Pacific Open champion Wozniacki delivered a combination of power and precision to set up a meeting with Carla Suarez Navarro.
Seventh seed Petra Kvitova, also defeated by new world number one Kerber in the US Open, made light work of getting past Madison Brengle 6-3 6-3.
The two-time Wimbledon champion took all three break point opportunities and did not lose a solitary service game to ensure she will face Olympic champion Monica Puig for a place in the quarter-final.
Fifth seed Madison Keys made an early exit, failing to win two match points as she went down 6-3 3-6 7-6 (9-7) against Yulia Putintseva, but Dominika Cibulkova, eyeing a place in the WTA Finals in Singapore, came back from a set down to see off Lucie Safarova 4-6 6-1 7-5.
Anastasia Pavlyuchenkova advanced when Andrea Petkovic retired at 6-4 2-0 down, while Barbora Strycova, Elina Svitolina, Anastasija Sevastova and Magda Linette also moved into round two along with Aliaksandra Sasnovich.