SINGAPORE - After a pair of marathon three-setters on Monday, Angelique Kerber, and Madison Keys rolled to straight-set wins on Tuesday at the WTA Finals.

In the first match, Kerber wore down Simona Halep in a 6-4, 6-2 win. The German broke open a close first set and never looked back winning nine out of the last eleven games in the match. Grinding down Halep from the baseline, the world no. 1 seized control of play, turning the match after the Romanian gained a 4-3 lead in the opening set.

Kerber quickly bolted out to a 2-0 lead in the second set before Halep could scratch the scoresheet. And despite attempts by Halep to rally, Kerber never lost her serve in the set and picked up an insurance service break late.

“She's always a tough opponent, and I'm very happy to have my second match win here,” Kerber said afterward.

The win places her in a strong position to gain a spot in the semifinals, as she moved to 2-0 in the competition. Kerber shook off a sluggish opening match on Sunday and reminded many as to how she overtook Serena Williams at the top of the rankings this season as she confidently turned the match in her favor.

In the second match, Madison Keys overpowered Dominika Cibulkova 6-1, 6-4 to pick up her first win in the Red Group. Winning 86 percent of her first serve points, including six aces, Keys kept the Slovak on her heels for much of the match.

In the first set, Keys pounded Cibulkova with thundering forehands from the baseline and gained an early break. She kept her foot on the gas earning a second break before closing out the set in just 23 minutes.

Cibulkova would battle back in the second set but could not find any ground in her return game as Keys continued to serve big. Meanwhile, the American would find the one service break she would need to gain a 3-2 advantage and would not relinquish her lead the remainder of the match. She did not face one break point in the encounter.

“That was a little bit better than the first round,” said Keys. “I’m definitely really happy with how I kind of turned things around.”

After Tuesday’s Red Group results, Kerber sits at 2-0 while Keys and Halep still have a shot at the semifinals at 1-1 each. Cibulkova is not mathematically eliminated but has an uphill battle at 0-2 in the competition.

The White Group returns to the court on Wednesday when Karolina Pliskova faces Svetlana Kuznetsova while Agnieszka Radwanska will meet Garbine Muguruza.