Madison Keys' Midwestern revival continued with a 6-2, 6-4 defeat of Elena Rybakina in 1 hour and 31 minutes to reach her second Western & Southern Open semifinal.

The American won the biggest title of her career to date at Cincinnati 2019, and this result took her overall record at the tournament to 17-7, or 71% -- her best by some distance among the WTA 1000 events. Keys will next face Petra Kvitova in the semifinals.

Here's a snapshot of the key numbers from Keys' win.

9: Career semifinals at WTA 1000 level or above for Keys. Having also made the Australian Open last four in January, this marks the first time she has made more than one such semifinal in a single season since 2018.

2: Wins over Rybakina in as many meetings for Keys. Both occurred this year, but while their Roland Garros third round was a top-quality barnburner that required a match tiebreak before Keys advanced 3-6, 6-1, 7-6[3], this encounter was rather more one-sided.

5: Keys' last five semifinals have all come on hard courts. The last time she made the last four of a tournament on a different surface was in capturing the 2019 Charleston title on green clay.

12: Minutes that the opening game lasted, one-third of the length of the entire first set. Keys eventually navigated eight deuces to capture the Rybakina serve on her fourth break point, smacking clean return winners on two of the last three points.

21: Winners Keys struck over the course of the match, to only 11 for Rybakina. Her return of serve was particularly potent, and few of the Wimbledon champion's second serves went unpunished. Keys also rose to the occasion on crucial points. Having gone down 2-0 in the second set after a spate of errors, another clean return winner sealed the immediate break back, starting a five-game run that took Keys to the brink of victory at 5-2.

41: Rybakina's first serve percentage, which in light of Keys' returning made the Kazakh especially vulnerable. That first delivery remained formidable -- Rybakina dropped only eight points behind it, and it was largely responsible for keeping the scoreline as close as it was -- but there simply wasn't enough of it.

25: Unforced errors for Rybakina, compared to 16 for Keys. Rybakina's forehand was particularly awry in the first set; a shank from that wing handed over the double break for 3-0, and the final game of the set saw her net it on three of the last four points.

Kvitova powers past Tomljanovic

Petra Kvitova followed with a 6-2, 6-3 win over Ajla Tomljanovic to book a semifinal meeting with Keys. Kvitova had 29 winners to Tomljanovic's seven in the 1-hour and 13-minute clash.

Watch: Top winners from Kvitova's quarterfinal victory

Two-time Wimbledon champion Kvitova, who saved a match point in her first-round win over last year's finalist Jil Teichmann, moves into the Cincinnati semifinals for the third time, though she has yet to reach a final at this tournament.

Keys and Kvitova's head-to-head is deadlocked at 4-4. Their most recent meeting came in the first round of this event last year, where Kvitova prevailed in straight sets.

"We played first round last year here, so I think this is much, much better to play in the semis," Kvitova said. "I think she's really on fire. I love how Madison is playing. I think that she is one of the, like game playing, like one of the best. 

"I think she is really playing very beautiful. It's nice to see her in the semis, for sure. Unfortunately I'm playing her, but we will see tomorrow," Kvitova said with a smile.