LUXEMBOURG - Qualifier Eugenie Bouchard is through to her second semifinal of the year at the BGL BNP Paribas Luxembourg Open, advancing into the final four after Andrea Petkovic was forced to retire in the second set.

The Canadian came into the matchup with three qualifying and two main draw victories under her belt - having scored five wins in a row for the first time since her breakthrough 2014 season.

But she found herself in trouble against the resurgent Petkovic, who owned a 5-1 lead in the pair’s head-to-head record. Despite dropping the opening set, Bouchard kept herself in it as a left thigh injury caught up with her opponent, advancing 4-6, 4-0 (ret).

Read more: Goerges edges past Vekic, into Luxembourg semifinals

“It’s unfortunate that she had to retire - and I know the feeling, I’ve had to do the same a few times in the past,” Bouchard said after the match. “It’s the worst feeling as an athlete, to not be able to play anymore. I’m very sad for her and I hope that she can start next year strong.

“It’s weird to win this way, it doesn’t feel amazing. But I’ll wake up tomorrow in the semifinals and be excited to have another chance.”

Bouchard was broken early as Petkovic roared ahead to a 3-0 lead, converting her third break chance in a marathon game that went to deuce six times. But Bouchard broke back at 3-2 to get them back on serve, sparring with Petkovic from the baseline with her booming forehands.

But the German kept Bouchard’s serve under pressure throughout, stepping in on every short ball, and finally was rewarded with another break - this time at 5-3 putting her in the position to serve out the set.

Petkovic quickly zoomed ahead to a 40-0 lead, but Bouchard dug her heels in to save all three break points and extend her stay in the encounter.  Petkovic recovered to comfortably take the opening set.

The tables started to turn in the second set for Bouchard as she finally found her range, but just as the Canadian was looking set to mount a comeback her opponent seemed to tweak her left thigh, at 2-0. Petkovic took a medical time out for treatment, and returned to hit two double faults in a row before being broken. She was visibly struggling as another game went Bouchard’s way, before she was finally forced to retire trailing 4-6, 4-0.

The win not only sends World No.108 Bouchard into her second semifinal of the year after Gstaad, it also confirms her place back inside the WTA’s Top 100 for the first time since January of this year.

“It’s hard, I’ve played six matches in six days - even in Grand Slams you don’t do that because you have days off,” Bouchard said. “But that’s the position that I had to be in coming from qualies. Hopefully as my ranking goes up I won’t have to do that anymore.

“Matches is what I need right now, though. I’ve missed a couple of months here and there because of injury, and I did some good training before coming here. This is exactly what I wanted, matches. I can’t ask for anything more.”

Up next, Bouchard will face the No.1 seed Julia Goerges in the semifinals. The German was tested by Donna Vekic but prevailed in three sets, 6-3, 3-6, 6-3.