STUTTGART, Germany - Simona Halep closed out the night session on Wednesday with a hard-fought comeback against 2017 Wimbledon semifinalist Magdalena Rybarikova, 4-6, 6-2, 6-3, to reach the quarterfinals of the Porsche Tennis Grand Prix.

"She played really well in the first set; she's always been a really tough opponent for me," Halep said during the on-court interview. "I just wanted to keep the ball in, and play more to her backhand. I tried to stop missing because I was missing a lot at the start of the second set. From there, I was able to find the rhythm and play point by point."

Halep was fresh off of a successful Fed Cup weekend that saw her lead Romania back into World Group against Switzerland, but Rybarikova had already adjusted to the tour's pre-eminent indoor clay court, having knocked out BNP Paribas Open runner-up Daria Kasatkina in the first round.

"It's very slippery and in the first set at 3-3, I felt a muscle in my leg. It was tough to keep playing, but I didn't want to stop. I stopped thinking about the injury and kept playing. It's tough on this court, and I've never played my best tennis on it. But if you get used to it, you can get to be on a good level."

Shaking off a medical timeout for a right hamstring injury, Halep recovered from a set and a break down, winning the final five games of the second set and finding her footing after an early exchange of breaks to start the third. Serving for the match, she converted her first match point to become the first of the field to reach the last eight after one hour and 52 minutes on court.

"The final set was good and I think I played smart," she said in post-match press. "I played how I had to from the beginning but I ended up starting to play flat with no angles at the beginning and that's why I couldn’t take the first set. Then I changed the tactic and felt really really better."

In all, the top seed continued to show off her increased aggression, striking 34 winners to 24 unforced errors while forcing the crafty Rybarikova into 22 unforced errors while withstanding 19 winners. She won six of 10 break points while maintaining a solid 72% first serve percentage to book a clash between defending champion Laura Siegemund or CoCo Vandeweghe.

"Mentally I’m okay. Since I came here I’m sleeping non-stop, honestly. I didn't practice that much, only 45 minutes yesterday and today about 40 minutes. So, it’s not that much but if I’m fresh mentally I can play better tennis. I have to get used to this court which is tough. 

"I’m looking forward to playing another match, to be better on court, but still it’s not coming straight away. So, I hope next round I don’t play Siegemund again because it’s going to be the third year in a row. But maybe I’ll win this time."