The No.9-seeded Kvitova was the first to move through, beating No.5-seeded Sara Errani in a two-hour, 27-minute grinder, 64 67(3) 63. Kvitova looked headed for a straight set win as she built an early 64 31 lead, with Errani battling back to take the second set in a tie-break - but Kvitova's big hitting was just too big in the end for the Italian, who fell behind 4-1 in the third and never really recovered.
"I felt like I played very well at the beginning of each set, but then there were some turning points and she would start playing better, and I would make some easy mistakes," Kvitova said. "It was really up and down today - a big fight - but I expected that. I just kept fighting and I'm happy to win today."
The match numbers defined a stark contrast in playing style - Kvitova had five times the winners (65 to 13) and just over three times the unforced errors (61 to 19). Luckily for the Czech those ratios fell on the right side, and she maintained her mastery over Errani, now 6-0 in their head-to-head series.
Just nine minutes after Kvitova won it was the No.4-seeded Li's turn to win, edging No.13-seeded Sabine Lisicki in a very tight two-setter, 75 64. Things looked dicey at the end as Lisicki fought off Li's first match point with a huge forehand winner and ended up holding two break points to even the match at 5-all in the second set - but Li stayed calm and managed to close the match out in that game.
"It's always tough to play against her - she has a huge, big serve, and also forehand," Li said. "She broke my rhythm a little bit today. I need three or four shots to get my rhythm, and sometimes she just comes and shoots the ball in one shot. So I was a little bit shocked, but I'm really happy to win.
"I don't think either of us played to the best of our ability, but we worked really hard on the court, and I'm very glad to see that no matter how close the score was, I stayed calm and controlled myself."
Li leads Kvitova in their head-to-head series, 3-2. The pair is tied 1-1 on hardcourts, though.
"I'm looking forward to it - I like Li Na, we are good friends," Kvitova said. "She's a great player, so I'm looking forward to a great match and a great fight, and I hope we can show our best tennis."
"I just finished today's match, so I'll just enjoy this victory and won't think too much about my next opponent," Li said. "I have a day off tomorrow and my coach and team will give me full preparation."