NEW HAVEN, CT, USA - Two-time Wimbledon winner Petra Kvitova put on a vintage display of aggression to outlast fellow former World No.2 and 2016 champion Agnieszka Radwanska, 6-1, 7-6(3) at the Connecticut Open.

Kvitova has lifted the trophy three times in New Haven, and kicked off her quest for a fourth title in emphatic fashion on Monday night, surviving her longtime rival in one hour in 28 minutes on Stadium Court.

"I'm glad I made it in two," she admitted. "I didn't want to be on court much longer. She's a great mover and she's gets a lot of balls.

"I had to fight in the second set when I was down and I had to wait for a chance to break. Then I needed to play well in the tie breaker. It was just about a few points.

"When she plays longer, she plays better and better."

The two were facing off for the 13th time; while Kvitova won their most recent encounter at the Qatar Total Open in Doha, Radwanska dropped just two games back in 2016, when Radwanska went on to win the title in New Haven.

Three time New Haven champion @Petra_Kvitova books her place in the second round of the @Connecticutopen!



Seals the win over Radwanska 6-1, 7-6(3)! pic.twitter.com/7VN3ajY8N2 — WTA (@WTA) August 21, 2018

While Radwanska has struggled with health and consistency throughout this season, Kvitova is in the midst of a career renaissance, returning to the world's Top 5 on Monday after winning five titles on all surfaces.

That form was on display from first ball as Kvitova struck a stunning 16 winners to capture the opening set, and withstood a tough test from the Pole in the second set.

Rallying from 3-1 down in the second, the Czech powerhouse forced a tie-break and edged through the sudden death to book a second round clash with Kazakh qualifier Zarina Diyas.

"My serve went OK, but I struggled at the beginning of the second set," she said. "I found a rhythm, and that helped me a lot. I played easier games on my serves and that saved me energy."

After a tough week in the heat of Cincinnati, Kvitova, who overcame Serena Williams, Kristina Mladenovic and Elise Mertens in Ohio before bowing out to Kiki Bertens after three tough sets, admitted the grind of the season is beginning to take a toll.

"I'm a bit tired. Playing the night match helped me - I could have a nap during the day!" she joked before reflecting both on her strong record in New Haven, where she has won three times, and overall.

"When you come somewhere you know you play good tennis. It always helps you - the confidence is there.

"It was a tough loss against Kiki but I think I'm playing well."

Ahead of the meeting with Diyas, she is mindful of her overall condition and the looming US Open.

"There's been a lot of matches - not only the last week but since the beginning of the season - and I need to take care of my body," she added. "I'm trying to get massages, sleep is important. Small injuries are always there, so we just need to deal with that."

She has met Diyas only twice previously, sharing one victory each, with Kvitova taking the honors when they last met, at the French Open of 2014.