Maria Sakkari, aiming to improve on her WTA Finals semi-final run last year, opened the season-ending event Monday with a straight sets round-robin victory over Jessica Pegula. Greece's Sakkari, ranked fifth in the world, toppled third-ranked American Pegula 7-6 (8/6), 7-6 (7/4). Action in the Nancy Richey Group continued later Monday at Dickies Arena with Tunisian world number two Ons Jabeur -- a finalist at Wimbledon and the US Open this year -- taking on seventh-ranked Aryna Sabalenka.
In a rematch of the WTA Guadalajara final won by Pegula last week, she and Sakkari traded six service breaks in the opening set, Pegula twice recovering a break before Sakkari put it away in the tiebreaker.
After pocketing the first, Sakkari raced to a 3-0 lead in the second set before Pegula, who survived match points to win three times this season, broke back to trim the deficit to 3-2.
Pegula saved a pair of match points against her serve in the 12th game to force the tiebreaker, the second with a stinging backhand winner.
But Sakkari sealed it on her third opportunity when Pegula's effort found the net.
"It's never easy against Jess," said Sakkari, who improved to 4-2 against the American. "She's an amazing player. She's very confident right now. I knew it was going to be extremely tough but I fought hard and trusted my game.
"I was well-rested compared to the previous match. I'm very excited to start with a win here."
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