CHARLESTON, S.C. — Madison Keys got much more than she expected at the Volvo Car Open, leaving with her first championship in two years and a successful reunion with coach Juan Todero.

Keys was unsure how she would handle the season's first clay-court event — clay is not among her favourite surfaces — or if she'd mesh again with Todero, who had worked with her in 2013 and 2014 and was back in her corner this week after five years apart.

Any concerns were allayed when the 24-year-old American overpowered the normally steady Caroline Wozniacki 7-6 (5), 6-3 on Sunday.

"It was a really good first week," Keys said with a smile. "I hope we keep this up."

If they can, who knows what Keys might accomplish?

Keys, seeded eighth and ranked 18th in the world, continually hit big serves — she reached 121 mph — and overwhelming forehands to wear down the fifth-seeded Wozniacki of Denmark and win her fourth career WTA event.

The match turned after Wozniacki rallied from 0-30 down and survived three deuces to move in front 6-5 in the opening set. Keys steadied herself and won four straight points to set up the tiebreaker.

Keys fell behind 2-0, then won six of the next seven points including a backhand winner that Wozniacki let land inside the baseline while in good position for a shot. Keys closed the set with a crisp forehand.

Wozniacki said she believed Keys' shot was drifting long. "Sometimes you miscalculate in a bad moment," the former world No. 1 said.

The second set was more of a runaway for Keys, who won four of the final five games. She won four consecutive points to break Wozniacki's serve, then won four more points to lead 5-2.

Wozniacki could not respond.

Keys was "just too good for me," said Wozniacki, who had beaten Keys in their only two previous meetings.

Keys beamed and bent her knees and elbows in celebration after putting away Wozniacki's return at the net on match point.

Her first win of the season continued a curious trend on the WTA of 15 different winners for the tour's first 15 tournaments this season.

It had been a disappointing stretch for Keys, whose best showing so far was reaching the round of 16 at the Australian Open.

She spent about 10 days working with Todero on clay before arriving in Charleston and believed their reunion might lead to positive results. Not even she envisioned this run, in which she defeated 2017 U.S. Open champion Sloane Stephens in the quarterfinals, 2016 Olympic champion Monica Puig in the semifinals and Wozniacki, the 2018 Australian Open winner, for the title.

"I try not to put expectations as far as results on myself," Keys said. "I just really wanted to play the right way and have a really great week of practice and trying to get some matches, and then obviously as time went, feeling more and more confident out there and walking away as the winner."

Keys said Todero's personality works well with hers. She owns her up-and-down moments and said Todero has a way of keeping her upbeat, laughing and focused on the good things possible instead of past problems.

Keys was proud not only of out-hitting Wozniacki, but out-strategizing her as well. Key said her opponent was one of the most difficult on tour as far as finding openings for breakthroughs on points because she is so precise and relentless. "I will be able to call on this going forward this year," she said.

As far as clay?

"Clay-court specialist," Keys joked. "It's definitely moving up on my ranking list of favourite surfaces."

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