consecutive baseline unforced errors to drop the set.
However at 1 all in the final set, Williams rediscovered her powerful aggressive game to win the last five games of the match.
For the match, the American had won 22 of 31 net points.
In her fourth round match, Kvitova upset the reigning ladies’ Wimbledon champion and third seeded Garbine Muguruza of Spain 7-6(7-3), 6-3 behind many powerful groundstrokes of her own.
Head to head, Kvitova leads Williams 4-1. However all five matches have gone three sets with Kvitova taking the last meeting in a 2014 third round encounter at Wimbledon 5-7, 7-6(7-2), 7-5.
Williams did not lose serve until the final game of the match after being two points from victory in set two.
The American has taken the first set in four of her five matches versus Kvitova and she will need another good start to avoid a deficit from which Williams may never recover.
One troubling statistic for Williams however is that she has lost a crucial tiebreaker the last three times she has faced Kvitova; twice in the final set and at Wimbledon in the middle set which would have given the American victory.
For both players holding serve will be key as will the ability to hit more winners than errors.
Look for Williams to step up her level of play as she moves one step closer towards her third grand slam final of this year after previously reaching the Australian Open and Wimbledon finals.