CINCINNATI, OH, USA - Ukrainian teenager Dayana Yastremska added another notable victory to her growing collection in the first round of the Western & Southern Open on Monday night, defeating former World No.1 Caroline Wozniacki, 6-4, 6-4.

In her Cincinnati main draw debut, the World No.32 walloped 27 winners across 20 games and broke serve six times, rallying from a break down in both sets to advance to a meeting with former US Open champion Svetlana Kuznetsova.

Read more: Dayana Yastremska on rising past family trauma: ‘It was really hard to play'

"At the beginning, I wasn't really comfortable on the court...with the way it was, the atmosphere. I just got into the game, and I tried to find my game, my rhythm, and that's what I was doing," Yastremska said after the match.

"I think that's what gave me some really good chances to prove myself, that I could find a really good rhythm, and make it. 

"I was expecting [her to defend well], because that's her style of game. Before the match, I knew she was going to do that. I tried to vary sometimes, not just playing really aggressive and hard...and I think I was doing this pretty good today." 

Yastremska lost serve in the first game of the match but won the next four to put herself in command, but nonetheless needed another late break - her third in Wozniacki's first five service games, to seal the opening set.

In the second, Wozniacki took a break lead twice, and led 40-15 in the eighth game to extend her lead to 5-3, but was ultimately downed by fearless hitting from the teenager down the stretch. 

"I think it's going good," the teenager said of her summer, after reaching the quarterfinals of the Rogers Cup in Canada.

"I've p;ayed a couple of matches and I hope I'm going to play a couple of more here. Definitely, the goal is to make a good result at the US Open. I'll try to play great here and make it as good as possible to prepare for the US Open."

The 19-year-old will next match wits with another Grand Slam champion in Kuznetsova, who overcame No.11 seed Anastasija Sevastova in over two-and-a-half hours, 7-6(3), 6-7(4), 6-4.

"I never played with her or practiced with her, but I know she is a very strong player," Yastremska said. "I'm just going to stay the same: go on court, fight and just play my game."