NEW YORK, Nov 8 - Coco Gauff survived a tough test from Jessica Pegula 6-4 6-7(5) 6-2 on the first day of round-robin play at the WTA Finals on Sunday, as Czech Linda Noskova cruised past Marta Kostyuk 6-2 6-4 in Indian Wells.

Gauff beat Pegula just three months ago in Cincinnati and had the right formula again, as the 2024 winner showed superb versatility in a clash between the top two Americans in the season-ending championship.

The frequent rivals were 5-5 in head-to-head before Sunday and appeared perfectly matched through a tight opening set, where Gauff got the break from the baseline on the fourth set point.

Pegula took back the momentum, winning the first three games of the second set before Gauff dug in her heels, trimming the lead to 3-5. Gauff saved three set points in the 10th game to level it, finding her best tennis from the baseline.

Gauff saved another two break points and shouted in celebration as she clinched the marathon, 10-minute 11th game. But Pegula saved match point in the 12th and found another gear in the tiebreak, taking the set with a lethal shot down the line.

Up a break in the third set, Gauff extended her lead to 5-2 when she ran up to the net and forced her opponent into an error. She capped a terrific show with a triumphant roar as Pegula sent one past the baseline on the third match point.

The eighth-ranked Noskova is keen for another accolade after her breakthrough win at Wimbledon this year and she got off to a fine start in her WTA Finals debut, applying pressure from the baseline and at the net.

The pair traded early breaks before Noskova slammed her foot on the gas in the first set, where Kostyuk was unable to hold her serve until the seventh game.

The Ukrainian Kostyuk was a late addition to the competition after world number one Elena Rybakina pulled out sick, and she was never able to settle in against the Czech, who sent across 20 winners and sealed it with an unreturnable forehand strike to the back corner.

"I definitely wanted to give this week one last push of the season. It's a long year, we all are kind of drained and injured and all the things together, but it's one of the most important tournaments of the year," said Noskova, who reached the semi-finals at Indian Wells earlier this year. REUTERS