TORONTO, Canada Czech qualifier Marie Bouzkova rounded out the four semifinalists at the Rogers Cup as No.4 seed Simona Halep succumbed to injury on Friday night.

The 21-year-old won the opening set against the Wimbledon champion, 6-4, after breaking serve three times, before the World No.4 retired from the match with a lower left leg injury.

"I felt [Achilles problems] since the first match here. Today I felt it more, so that's why I decided to retire," Halep said. Tomorrow, it would have been Serena and it is not easy."

Bouzkova led 4-0 in the opening set before Halep won four games in a row of her own to level the set, but won the last two games to win her 11th consecutive set in six matches so far this week.

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"Of course I'm disappointed that Simona had to retire today. As I said on the court, I really enjoyed playing against her, even if it was just for one set. It was great experience, and now I'm looking forward to playing against Serena," Bouzkova said after the match.

"We had real long rallies. So maybe it was just something that she wanted to prevent going to the second set and going, you know, fighting more. So she was just scared, you know, to get it worse.

"Serena has been my role model growing up. The way I play, you know, my technique, you know, is little bit -- you know, the backhand is little bit similar to hers. I'm just going to try to enjoy as much as I can tomorrow and put up a fight."

The shortened match is the first career victory over a Top 5 player for the World No.91, as she previously scored her first Top 10 victory against Sloane Stephens earlier this week. 

"I think my game has gotten more and more confident after every match. You know, today I think was the best set that I played here," Bouzkova said. 

"I was able to defend a lot of balls and as well be aggressive. So that's something that's been, you know, getting better as I got through the tournament.

"I'm just enjoying more and more, getting more confident with my game. I feel much better going to the center court now than I was on the first match, so that's something that helps me as well.

"I feel very confident on the court. I get used to them. I got used to the center court. That's something that really helped my game that I could go for my shots but as well defend well and just pick the right times to be aggressive.

"As I progressed in this tournament, I got more confident doing so. That's for sure something that's been the key to my victories here."