Sloane Stephens produced a fine comeback to book her place in the final of the WTA Finals with a three-set victory over Karolina Pliskova.
The 2017 US Open champion went into the encounter in superb form, having won all of her group matches en route to the last four in Singapore.
However, she appeared bewilderingly short of her best as she was bagelled in the first set, Pliskova taking the first eight games of the match without reply.
The tide turned in her favour, though, and Stephens won six of the next eight games to push the match to a third set, before dominating the decider to prevail 0-6 6-4 6-1 and book a final meeting with Elina Svitolina.
Pliskova needed just 31 minutes to wrap up the first set without dropping a game, her powerful and accurate groundstrokes allowing her to consistently dictate the rallies as Stephens, hindered by a lack of footwork that has often been a problem for the American, struggled to make any impact beyond stringing together errors.
Stephens was resigned to the bagel as Pliskova sealed it with a forehand smash at the end of another dominant point, standing forlornly at the baseline as the Czech hammered the ball into the open court.
The second set looked poised to follow a similar pattern as Pliskova made it eight games in a row, but Stephens finally stemmed the tide and broke when a rare errant forehand came off the racquet of the former world number one.
She then staved off a break point to level at 2-2 and subsequently broke to love as the momentum swung firmly in her favour thanks to Pliskova spraying narrowly wide again.
Stephens gifted Pliskova an immediate break back by sending a lazy backhand long, but a double fault returned the initiative to the world number six and she held firm to force a decisive set.
Pliskova committed 21 unforced errors in the second and she was no more composed in the third as both players proved unable to hold serve until Stephens did in the fourth game with an ace to take a 3-1 lead.
Prior to that Stephens hold, Pliskova's coach Rennae Stubbs had told her player: "This is all about courage now. How deep do you want to dig?"
Yet Stubbs' words failed to have the desired impact and a double fault handed Stephens a commanding 4-1 lead.
Her confidence and full range of movement completely rediscovered, Stephens raced to the final two games as Pliskova, resigned to her fate like Stephens in the first, ballooned a forehand wide.