Petra Kvitova sprayed winners early, then survived a lengthy dip in form to defeat Zarina Diyas 6-1, 5-7, 6-2 to reach the New Haven quarterfinals.
Kvitova looked as though she would cruise to victory after smashing winners to all parts of the court in the early stages. She needed just 26 minutes to close out the opening set and jumped ahead 2-0 in the second set; the No. 3 seed then had a break point to go ahead 3-0.
But she couldn’t convert it and lost her serve four times in the set, including on consecutive occasions after breaking. On the first of those, she double faulted away her lead, and on the second, while serving for the match, she was broken at love.
Diyas’ strong form disappeared again in the third, however, as Kvitova broke twice to open the set and faced just one break point — which she saved — the remainder of the way.
The numbers told a mixed story. Diyas won fewer than half of first serve points — to 70 percent for Kvitova — but the Kazakh qualifier won far more second serve points than Kvitova’s 10 of 30. The world No. 5 hit 14 winners to six unforced errors in the first set, but tallied nearly three dozen errors in the subsequent set.
Nevertheless, she advanced against a qualifier playing her fourth match in Connecticut, setting up a quarterfinal with Carla Suarez Navarro on Thursday. The veteran Spaniard will likely pose the toughest test yet for the three-time New Haven champion.
Earlier, Olympic champion Monica Puig beat Anett Kontaveit 6-4, 6-3 in a match with 10 breaks of serve. Puig lost a 3-1 lead in the opening set but won the last three games to secure the frame, then stormed back after losing her opening service game in the second set.
Puig hit just 13 winners to 29 unforced errors, but Kontaveit was barely better and won fewer than half of points on her first serve. The Puerto Rican, who came through qualifying, meets No. 2 seed Carolina Garcia next.
