INDIAN WELLS, Calif. – The WTA Finals began on Sunday and all eight competitors in singles and doubles have played at least one round. Jessica Pegula and Marta Kostyuk have played two.

This tennis tournament is one of the few where every player faces the other players in their group of four. A player can lose two of three round-robin matches and still advance. Eight times, a player who went 1-2 in the round robin has gone on to win the title.

The top two players in each group move on to the semifinals, based on wins. If two players are tied for second, the head-to-head result decides it. If three are tied, the tiebreakers are percentage of sets won, then percentage of games won. Read more about who made it in this year.

Coco Gauff d. Jessica Pegula, 6-4, 6-7 (5), 6-2
Gauff won the first set, saving four break points. Pegula saved four of five and that made the difference in the set. In the second, Pegula jumped to a 5-1 lead before Gauff came back to go up 6-5 with a match point. Pegula pulled out the set in a tiebreaker before losing the third, getting broken three times to Gauff’s one.

Linda Noskova d. Marta Kostyuk, 6-2, 6-2 (Sunday)
Kostyuk struggled with her serve, especially in the first set, when only about one quarter of her first serves (27%) went in, and that cost her. In the second set, Noskova won her only break-point opportunity. Kostyuk’s serving improved and she had more winners than Noskova (11-10), but she couldn’t convert on either of her break-point chances.

Aryna Sabalenka d. Karolina Muchova 7-6 (2), 7-5 (Monday)
Muchova, playing in the WTA Finals for the first time, had similar stats to Sabalenka but couldn’t get over the finish line in either set. In the second set, Sabalenka won the big points, breaking Muchova’s serve three times. Muchova broke Sabalenka twice.

“You don't get an easy match here, so this is like the first first match, and you play the world number two, so you don't have that time to get in a match or … grow your game, so .. right away [you] have to play your best tennis,” said Muchova. “But I'm happy. I got this match now under the belt.”

Mirra Andreeva d. Elina Svitolina 6-4, 6-0 (Monday)
Finals newcomer Andreeva continued to get stronger as the much progressed. She was never broken and won seven straight games to close out the match.

“I think actually because I was nervous, maybe the nerves helped me to try and be more consistent in a way, like I didn't try to go for some crazy shots or didn't try to play risky,” said Andreeva. “I feel like in a way that helped me.”

Gabriela Dabrowski/Luisa Stefani d. Elise Mertens/Zhang Shuai 6-3, 7-6 (5)

Hanyu Guo /Kristina Mladenovic d. Su-Wei Hsieh/Jelena Ostapenko, 3-6, 6-1, 12-10

Sara Errani/Jasmine Paolini d. Katerina Siniakova/Taylor Townsend, 4-6, 6-1, 10-8

Cristina Bucsa/Nicole Melichar-Martinez d. Ellen Perez/Demi Schuurs, 6-0, 6-4

Pegula vs. Kostyuk, 6-2, 7-5
Kostyuk had a slow start with four double faults in the first set. She came back in the second set to go up 4-2, but Pegula broke back to stay in the set, eventually winning it, 7-5.

Gauff vs. Noskova

Siniakova/Townsend vs. Perez/Schuurs

Bucsa/Melichar-Martinez vs. Errani/Paolini

Svitolina vs. Muchova
Sabalenka Vs. Andreeva

Dabrowski/Stefani vs. Guo/Mladenovic
Hsieh/Ostapenko vs. Mertens/Zhang