Shenzhen - Wimbledon champion Simona Halep saved a match point in the second set and then powered to a rousing comeback victory over Canadian sensation Bianca Andreescu at the WTA Finals on Monday.
The No 5 seed prevailed with a gruelling 3-6, 7-6 (8/6), 6-3 win in two hours and 34 minutes at the Shenzhen Bay Sports Centre.
Andreescu, who at 19 is the youngest player in the draw, had a match point in the 12th game of the second set but was unable to convert and fell away after that.
Halep moved top of the Purple Group alongside defending champion Elina Svitolina who earlier beat No 2 seed Karolina Pliskova 7-6 (14/12), 6-4 in one hour and 53 minutes.
"Today it was a challenge because she's 10 years younger than me," Halep told reporters. "It was a good fight. I'm happy about my victory."
There has been much attention on Andreescu since she beat Serena Williams in the US Open final and she started confidently in her first appearance at the season-ending showpiece.
In a matchup of the past two Grand Slam champions, Andreescu dictated early from the baseline and ruthlessly pounced on Halep's tentative serve to break three times in a dominant opening set.
It was a see-saw in the second set with both players struggling to hold serve before Halep produced her best when it mattered most to force a deciding set.
Andreescu received medical attention on her lower back between sets and she appeared lethargic in the deciding set as a rejuvenated Halep took full advantage.
"I didn't take my chances in the second set, so I'm really disappointed about that," said Andreescu who declined to go into details about her back injury.
The No.4 seed lost for just the sixth time in 54 matches this season, where she started the year ranked 178.
Earlier, Svitolina continued her dominance over Pliskova to start her title defence impressively. It was Svitolina's fourth straight victory over a misfiring Pliskova who had 42 unforced errors.
The 25-year-old is hoping to end a barren season on a high having not captured a title since last year's WTA Finals triumph.
"This is my last chance (this season)," Svitolina told reporters. "That's the biggest motivation for me. I always try to bring my best game."
It was a disappointing result for Pliskova who started well, mixing trademark hard-hitting blows from the baseline with softer touch, but Svitolina slowly clawed her way back into the match.
It was a tense contest extending into a nerve-jangling tiebreaker with Pliskova's bold approach saving six set points, but she miscued on the seventh as the Ukrainian finally drew first blood.
A frustrated Pliskova was broken immediately to open the second set and never seriously threatened to stage a comeback against an increasingly confident Svitolina.
Pliskova, who has a tour-leading four titles this season, rued the marathon tiebreaker where she failed to convert a set point.
"I think that decided the match," she said. "Even though I had some chances in the second set, the first set was a big part of the match."
Result from WTA Finals tennis in Shenzhen on Monday (x denotes seeding):
Elina Svitolina (UKR x8) bt Karolina Pliskova (CZE x2) 7-6 (14/12), 6-4