On the other side of the net from Radwanska was Kirsten Flipkens. Flipkens has had a whirlwind last several months on the WTA, ranked as low as No.262 last summer and now inside the Top 30 - and not only had she reached the biggest quarterfinal of her career this fortnight at the Sony Open Tennis, she had also taken out a Top 10 player to get there, upsetting Petra Kvitova in the third round.
And the No.30-seeded Flipkens looked like that momentum might carry her past Radwanska in this match as she stormed out to a 4-1, double break lead, eventually taking the first set, 6-4, and coming within two games of victory as she rallied from 0-3 to draw even with Radwanska in the second, 4-4.
But Radwanska came alive, rattling off seven straight games to take the second set and build a 5-0 lead in the third set, and after Flipkens squeaked out two games to close in a little bit to 5-2, it was all over in the next game as the No.4-seeded Radwanska broke one last time to take it, 46 64 62.
"She has had a very good two weeks and I knew it wasn't going to be easy tonight," Radwanska said. "I started a little slow and she was playing consistently well throughout the whole match. Then in the second set I finally started playing much better and more aggressive. I'm happy to get through."
Though their strokes aren't too similar, Radwanska and Flipkens do have one big thing in common - neither of them relies only on power. Radwanska commented on their strategic games after the match.
"I think she's a very smart player too, mixing everything up and playing some tricky shots as well," Radwanska said. "Every point we were running a lot. It was tough - there were no easy points."
And what about that miracle shot in the second set, which you can watch by clicking here?
"It was all so fast, it was really just one second to react," Radwanska said. "The ball hit the net cord and changed direction and I couldn't play a normal backhand, so I just turned around and did it. It was a bit of luck but I had no choice - I just put my racquet on it and that was it! It was pretty funny."
Flipkens had come into the tournament on a career-high of No.28 in the world, and will shoot up the rankings come next Monday to a new career-high of No.22 - just on the brink of her Top 20 debut.
Next up is the No.1-ranked, No.1-seeded Serena Williams. Williams has beaten Radwanska in all four of their previous meetings. Radwanska has only won one set in those four meetings, and even in that set she clawed back from 4-2 down - the middle set of the Wimbledon final last year.
"I think playing Serena is always a great challenge," Radwanska said of the five-time Sony Open Tennis champion. "We haven't played since last year so I'm really excited about this match."
"She doesn't miss," Williams said of Radwanska earlier in the day. "She gets every ball back and makes you fight for every single point. So I don't know anything that could be less dangerous."