The American beat Kerber 6-3, 6-3 becoming the first player since Garbine Muguruza in 2015 to win all three of her matches in the round robin.
In the second game, which Svitolina lost his serve in the Ukrainian three times played the break point (in total served 21 times).
"I think physically I was a little bit stronger. pushed myself a little bit more maybe mentally", Svitolina told reporters. I was just trying to get the ball back.
The trend of this tournament suggested the match would go to three sets, however - 10 matches have gone the distance this week, beating the previous high of six - and it duly did so when Svitolina ran away with the second set.
"But I was staying very positive and I think that's what made the difference this week".
Duke and Duchess of Sussex meet the orcs in New Zealand
Speaking to the Sunday Times newspaper, the source said: "If you have one private office trying to manage both, things get hard ". Minnie Newman, an 11-year-old from Kelburn Girl Guides, said she was impressed with Meghan . 'This is a good start, ' she added.
Stephens said she was satisfied with her debut WTA Finals.
Stephens will play the sixth seed Elina Svitolina in the showdown after the 24-year-old Ukrainian took more than two and a half hours to see off the eighth seeded Dutchwoman Kiki Bertens.
Naomi is a very smart girl, she figures a lot of things by herself, it wasn't me so much going in and talking to her about you know, "Don't do this, don't do that, think like that", no, she's very good at that. "I'll take it and I'll take my rest, and I have some more recovery time for tomorrow". It's just matter of whether she can rattle an opponent who has not dropped a match this week. It was Pliskova's first win over her compatriot in four matches between the two.
She struggled on the Singapore Indoor Stadium's hard court, which played slower than expected. And despite gobbling up points on the tour, she was towing a reputation as a Grand Slam underachiever who only won her place in the Singapore draw by default, when WTA No. 1 Simona Halep pulled out of the event at the last minute due to injury.
The world number seven from Ukraine has won all four matches in the season-ending tournament this week and believes she can improve her disappointing record in majors next year by adopting the same positive approach.
Svitolina split with coach Thierry Ascione in October and worked with Andrew Bettles in Singapore but said she would look at her options during the off-season.