Leading by a set and a break, Keys looked to be easing into the semifinals. However, a spirited Kvitova comeback ensured the match went down to the wire, Keys eventually closing out a 6-3, 6-7(2), 7-6(5) victory after two hours and 41 minutes.
"I think I played a pretty solid first set today, then she raised her level. I just think at the end it became a couple of points here or there. I think I got my serve back on track a little bit," Keys said. "I mean, really, it could have gone either way. It was really close."
Madison Keys' record in 3 set matches:
? WTA Insider (@WTA_insider) October 7, 2016
Keys' victory was all the more impressive given Kvitova's recent form. In Wuhan, she dismantled a series of higher-ranked opponents to win her first title in 13 months, before seeing off Wang Yafan and Garbiñe Muguruza this week to extend her winning run.
In Keys, though, she found an opponent capable of matching her firepower. After the first seven games went with serve, the American carved out the first break point by whipping a forehand return onto the line. Kvitova double faulted to surrender the break and ultimately the set.
Kvitova came roaring back in the second set, recovering from 4-2 down to level the match on a tie-break. The decider followed a similar pattern, Keys making the early running only to be pegged back when the Czech won the latest baseline slugfest. This time, however, Keys refused to be overwhelmed, surviving a series of arduous service games to reach the sanctuary of a tie-break. Locked at 5-5, she finally found the knockout blow, hammering a backhand down the line before serving her way into a maiden Premier Mandatory semifinal.
"I definitely think I got frustrated. You know, it's always tough when you're serving for a set and you have a bad game," Keys said. "Doing that a couple of times in a match is frustrating.
"But, you know, I think I did a really good job at staying focused and just trying to regroup and worry about the next point. You know, she made it really tough today. I'm just really happy that at the end I was able to get my serve back on track and get myself ahead in the tiebreaker."
Keys moves on to face Johanna Konta in the semifinals, knowing that a run to the title would secure her a debut at the BNP Paribas WTA Finals Singapore presented by SC Global.
"Jo is playing really well. I mean, at this point everyone's trying to qualify, everyone's trying to play their good tennis at the end of the year," Keys added. "Pretty much whoever you play is going to be a tough match."