It was a grueling and sometimes ugly affair, but top seed Agnieszka Radwanska is into the quarterfinals at the Western & Southern Open, defeating Sloane Stephens 6-1, 4-6, 6-4 in just under two hours today.

It was a disastrous start from Stephens, who at 19 is the youngest woman in the Top 50, and still new to the top echelons of the game — this time last year she was ranked outside the Top 100. Facing a top player for the first time is always a daunting experience: with some women, this might mean adjusting to the pace they can generate, with Radwanska, it means quickly learning that you need to hit four or five shots you might expect to be winners to take one point. Stephens double-faulted twice in her first service game to be broken, made 11 unforced errors against just 2 winners, and generally looked like she had no idea how to approach the match. As Radwanska took the first set 6-1, having won 24 points to 10, the top seed could justifiably look forward to getting out of the sun and back into the locker room in short order.

With the help of a visit from her coach between sets, however, Stephens settled and by virtue of doing the simple things well turned the one-sided contest into an entirely different match. Playing with a killer combination of aggression and accuracy, she broke Radwanska twice to lead 4-0, and we saw for the first time a major aspect of the match-up with troubling implications for the Pole: Stephens hits a heavy ball with plenty of spin, particularly off the forehand side, and it repeatedly kicked up above Radwanska’s preferred strike zone. Radwanska is not comfortable hitting a forehand when the ball bounces up above shoulder height, and she repeatedly drove the ball into the net trying to deal with it.

Radwanska is not world No. 3 (with a shot at the No. 1 ranking if she performs well here and in New Haven next week) for nothing, however. She is a problem-solver on the court and displayed that well today. Down 2-5 in the second, she began to mix up her shots a lot more, deploying backhand slices to get a low and attackable ball to her forehand and coming into net unusually frequently, even throwing in the occasional serve and volley. Stephens took the second set as Radwanska put a forehand long but the third set was a grueling war of attrition, exchanging breaks for 1-1 and 3-3 before Radwanska broke for the third time by attacking the net.

Stephens had a gold-plated opportunity to break back, but put what should have been an easy winner into the net from right on top of it, and Radwanska served the match out, finishing with a delicate backhand drop shot winner to reach her 13th quarterfinal of the year. Stephens will be disappointed that she couldn’t get the win against a Radwanska who was clearly bothered by her tennis, but winning has become a habit for Radwanska, who is into the quarterfinals for the first time in Cincinnati.

Hannah Wilks