CANCUN, Mexico -- No.3 Coco Gauff kicked off her GNP Seguros WTA Finals Cancun campaign with a bang after defeating No.6 seed Ons Jabeur 6-0, 6-1.

The victory is Gauff's first at the season-ending championships, having gone 0-6 in singles and doubles last year in Fort Worth. It is also her eighth Top 10 win of the year. Only her next opponent, Iga Swiatek, has tallied more.

WTA Finals: Scores | Draws | Order of play

Gauff has now won 50 matches this season, with eight coming against Top 10 opponents. She is the first teenager to win 50 or more matches in a single season since Caroline Wozniacki in 2009. She is also the first teenager to tally a singles victory at the WTA Finals since Wozniacki and the first American teenager to do so since Venus Williams in 1999.

In Cancun, Gauff is playing her first tournament since splitting with coach Pere Riba after the China Open. 

WTA

"Unfortunately, it wasn't my decision," Gauff said. "But we had to end the partnership. If it was up to me, I would have loved to have him here. But you know, things happen. Life happens. So no bad terms on our end.

"Sometimes people think it's bigger than what it is. But some things just didn't work out and that's all. I still think that he was a great guy. And obviously, he did amazing things for me personally and also for my game. So I'm sure he's going to be successful in his next step."

In her first meeting against Jabeur this season, Gauff needed just seven minutes to race to a 3-0 lead. With pin-point hitting into the corners, the US Open champion refused to allow Jabeur to weave her crafty web. Gauff did not face a break point and lost just three points on her serve in the 23-minute first set. In total, Gauff lost just nine points in the first set.

"Ons is a great player, so I felt really unsteady the whole match even though it didn't [look] like that," Gauff said. "But I'm just happy to finally get a win here in this event."

After Gauff held serve in the opening game of the second set to win her seventh consecutive game, the players left the court for a rain delay. On the resumption, Jabeur held serve to get on the board.

Hawk-Eye

But the respite was short-lived. Gauff broke Jabeur from a 40-15 deficit to lead 3-1. As she continued to target Jabeur's forehand return, Gauff protected her lead to secure a 57-minute win and improve her head-to-head record against the Tunisian to 4-2.

"She played really well," Jabeur said after the match. "She played a correct match, didn't make a lot of mistakes. On my part, I did make a lot of mistakes." 

Gauff will face No.2 Swiatek next in what will be the 10th career meeting between the two young champions. Swiatek opened play in the Chetumal Group with a resilient comeback win over Marketa Vondrousova, rallying from 5-2 down to win 7-6(3), 6-0.

Wednesday's winner will take control of the group.