The WTA Finals pits the top eight women in the world rankings against each other in Singapore. There was lots of sweat in steamy Lion City, where world number one Angelique Kerber took on fourth-seeded Romanian Simona Halep in her second Red Group match.

Angelique Kerber of Germany competes during the WTA Finals round robin match against Simona Halep of Romania at Singapore Indoor Stadium, Oct. 25, 2016. Angelique Kerber won 2-0. (Xinhua/Then Chih Wey)

Kerber got off to a quick start by breaking Halep’s opening serve, but Halep later broke back to level things at 4-4. Enventually, Kerber won the set 6-4.

At the start of the second set, once again Kereber got an early break as she sought to even her head to head record against the Romanian at four matches each. She lofted a backhand that Halep did not capitalize on and then had to scramble as Halep held firm at the net before the Romanian finally put away the overhead.

But despite a few blips like that, the set belonged to Kerber, who had match point. Halep’s return is called in but Kerber challenged and the review showed it was indeed out.

The top seed took the second set 6-2 for her second victory at the season finale and now only needs to win one set against Madison Keys to reach the semifinals. Later the German confessed that she is still getting used to her role as world number one.

Keys beats Cibulkova 6-1, 6-4

Dominika Cibulkova faced seventh-seeded American Madison Keys in another Red Group match.

Keys built a 4-1 lead in the first set. Keys lost her opening match to Halep, but she looked good here as she loaded up and delivered a big forehand en route to winning the set 6-1 in just 22 minutes.

And the Amnerican’s power and precision continued to be too much for Cibulkova, who did no better in the second set.

At match point for the American, a big serve opened the court for an easy winner. It finished 6-4 in the second set in a dominant display from the 21-year-old, who will need another performance like that on Thursday to beat Kerber and reach the semifinals.