Roberta Vinci, the 2015 runner-up, and two-time Wimbledon champion Petra Kvitova booked US Open third round spots Wednesday as Novak Djokovic and Rafael Nadal prepared for the latest tests of their battle-scarred seasons.

Seventh seeded Italian Vinci, defeated by compatriot Flavia Pennetta in last year's final, eased past Christina McHale of the United States 6-1, 6-3.

The 33-year-old, playing at Flushing Meadows for the 14th time, goes on to face either Yulia Putintseva of Kazakhstan or Germany's Carina Witthoeft.

Kvitova, the 14th seeded Czech who recorded her best performance in New York 12 months ago when she made the last-eight, beat Turkey's Cagla Buyukakcay 7-6 (7/2), 6-3.

Kvitova was in her trademark all-or-nothing mood, mixing up 31 winners with 30 unforced errors against her 26-year-old opponent who was the first Turkish woman to play in the main draw at the tournament.

Up next for Kvitova is Ukrainian 22nd seed Elina Svitolina who put out Lauren Davis of the United States 6-1, 4-6, 6-3.

Later Wednesday, defending champion and world number one Djokovic, who needed treatment on a right upper arm injury during his laboured four-set win over Poland's Jerzy Janowicz on Monday, faces Jiri Vesely of the Czech Republic.

Vesely inflicted a rare defeat on the Serb when he triumphed on clay at Monte Carlo in April.

"Different surface, different circumstances, best-of-five. But still, Vesely deserves respect," said Djokovic, the 2011 and 2015 champion in New York and looking for a third major of the year.

"He has a big game, big serve, big forehand, and moves well for his size. So let's see. Conditions are quite suitable to my style of the game. Hopefully I'll be able to slow his serve down a little bit and then take it from there."