Kvitova, the 2011 Wimbledon champion, also had to put in some overtime before winning her clash with Misaki Doi 6-2, 3-6, 6-1, while a grieving Ivanovic, the 2008 French Open winner, cruised to a 6-2, 6-0 win over Georgia’s Anna Tatishvili.
Ivanovic arrived in New York with a heavy heart after learning about the drowning death of a childhood friend back in her native Serbia.
“It’s been very sad news,” Ivanovic told reporters. “It was very hard because it was almost like my relative. We grew up, and I knew him since we were kids. It’s very, very sad.”
With her boyfriend, golfer Rory McIlroy, watching from the stands, Wozniacki had to dig deep to beat Chinese qualifier Duan Yingying 6-2, 7-5.
Wozniacki raced through the opening set in just 35 minutes then reeled off five games in a row to seal the win after falling behind 5-2.
“It’s not about being pretty,” Wozniacki said. “It’s about just getting the job done. I did that, so I’m happy about that.”
Wimbledon semi-finalist Jerzy Janowicz was booed for serving underhand in his 6-4, 6-4, 6-2 loss to Argentina’s Maximo Gonzalez, who is ranked 247th in the world.
Hampered by a painful back injury he suffered training three days ago, the Polish world No. 14 was in a foul mood, arguing with the chair umpire and throwing his water bottle on the court.
“I was in really good shape before this happened,” he growled. “That’s why I’m fricking disappointed.”