Angelique Kerber has 10 career titles and 10 years of experience more than Naomi Osaka, but the 30-year-old German believes that made little difference last night.
They are two places apart in the women's tennis rankings - Kerber is second, Osaka is fourth - and each has won two titles this year.
But, in a battle between the oldest and youngest of the eight singles players at this year's season finale, it was Kerber who triumphed after a 2hr 29min battle.
She beat the 21-year-old Osaka 6-4, 5-7, 6-4 to stay in contention at the BNP Paribas WTA Finals Singapore presented by SC Global.
Kerber, who lost her opening match in three sets to Dutch world No. 9 Kiki Bertens on Monday, said: "I don't know if (experience) was the reason, because (in my) first match here, I had a little bit more experience but, if you cannot take your chances, it's not always the best."
At the Singapore Indoor Stadium yesterday, she did.
The German, known for being one of the best retrievers on tour, was the steadier of the two - she hit 30 unforced errors to Osaka's 50.
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"It was a lot of ups and downs, a lot of emotions (in the third set)," said Kerber, who saved five break points to win the first set.
"It was just one, two points which decided the match. I was just trying to move well in the last few points and trying to go for it.
"But it was not so easy because Naomi is an incredible player and I knew before that it would be a tough match."
Osaka, the US Open champion, turned to herself, her coach and even her racket for answers - she at one point crouched down, gestured with both hands to her racket on the ground, and asked: "Why?"
On two occasions in the third set, the Japanese had two game points but eventually faltered - she hit four straight unforced errors to give Kerber a 5-3 lead.
The 2016 WTA Finals runner-up sealed the victory after she survived a cross-court rally that ended with an Osaka backhand into the net.
Said Osaka: "I'm a perfectionist - I expect a lot from myself and I feel like when other people expect a lot from me, it sort of doubles.
"I internalise a lot of things and then it just explodes and then I start talking to myself on the court."
She lost her first match here in three sets to American Sloane Stephens, and felt last night's battle was a continuation of that.
"I feel I didn't serve well in either of them," said Osaka.
"I'm proud of myself for being able to make the matches so close without really having a first serve, but I'm not really sure how that's going wrong and I want to practise it.
"I'm playing against the best players in the world.
"I feel like I want to be in top form but I'm not really there, so it's a little bit depressing."
Osaka's chances of progressing to the semi-finals of the US$7 million (S$9.65 million) tournament were kept alive by Stephens, who defeated Bertens 7-6 (7-4), 2-6, 6-3 in the second match.
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