Victoria Azarenka took a long and vital step towards the year-end world number one ranking by saving two match points in a heroic tussle against Angelique Kerber in the WTA Championships.
The top-seeded Belarussian beat the revelatory German 6-7 (11/13), 7-6 (7/2) 6-4 in an match full of magnificent rallies and surprises, which leaves Azarenka needing only one more victory to guarantee her a top finish.
Had Azarenka lost either of the match points against her a path might have opened up for the second-seeded Maria Sharapova to sneak through to the summit instead.
But despite repeated frustrations from Kerber's relentlessly courageous mixture of containment and counter-hitting, Azarenka somehow controlled her once unruly emotions and found a way to prevail.
"On the two match points against me I felt I had to go for it," Azarenka said.
"I wanted to change the momentum and take destiny into my own hands. I had a clear mind of what I had to do. It takes time to go through (what's needed) to learn that"
World number one Victoria Azarenka
"I felt she would not miss, so I didn't want to wait for her to make a mistake - I was determined to make it happen.
"I wanted to change the momentum and take destiny into my own hands. I had a clear mind of what I had to do. It takes time to go through (what's needed) to learn that."
With a difficult contest in prospect against Serena Williams on Thursday, that was essential.
A loss to the German on Wednesday and another one to the unofficial favourite from the United States on Thursday might have given Sharapova the opportunity to grasp the top-ranking accolade herself by winning the WTA title on Sunday.
Instead Azarenka denied Kerber both her match points by following up some sound serving with bold and courageous driving.
It helped atone for the four set points in a row and five altogether which Kerber enterprisingly denied Azarenka in a 24- point first set tie-break.
Even in the final set, when the top seed at last appeared to have acquired a winning momentum and twice forced breaks of serve, the superb contest was not over.
Twice Kerber broke back, and it required yet another muscle-stretching, lung-bursting push from Azarenka to force the outcome against her opponent's serve after three hours and six minutes of excellence.