STUTTGART, Germany – No.1 seed Agnieszka Radwanska started her clay season with a win over Germany’s Andrea Petkovic at the Porsche Tennis Grand Prix, winning 1-6, 6-1, 6-2 to make her way into the quarterfinals.

Their second round encounter was Radwanska and Petkovic’s sixth time competing against each other, with Radwanska staying undefeated against the German. However, all of those matches were contested on hardcourts, and Petkovic’s favored surface is red clay – four of her six titles have come on clay.

Playing on her favorite surface gave her an early edge – she won a drawn-out tug of war in the second game to break Radwanska’s serve and put the World No.2 down in a 3-0 hole. Petkovic covered the court, matching Radwanska’s famous variety shot for shot to take the first set.

The match took a turn in the second set, as Petkovic took a terrifying tumble just as Radwanska was finding her footing.

.@AndreaPetkovic takes a nasty fall, good news she's back up and playing! #PTGP pic.twitter.com/PX8fF0MLX2

— WTA (@WTA) April 21, 2016

“I slipped on the line and fell on my tailbone,” Petkovic explained after the match. “My ankle is okay, but my back is not so good. I just couldn’t move anymore.”

Though the German dusted herself off and continued on after taking a medical time out, Radwanska took advantage of Petkovic’s hampered movement and quickly closed out the set at 6-1 to level the match. It was one-way traffic from there, as the Pole dug from her arsenal of trick shots and booked her spot in the quarterfinals after almost two hours.

Radwanska sets up a quarterfinal clash against the big-serving Czech Karolina Pliskova. Pliskova extended her winning streak against Ana Ivanovic, cruising into the quarterfinals with a comfortable 6-4, 6-2 win.

More to come…