ISTANBUL, Turkey -- Pauline Parmentier of France moved into the semifinals of the TEB BNP Paribas Istanbul Cup on Friday after World No.2 Caroline Wozniacki of Denmark retired due to a left abdominal injury, with Parmentier claiming a 4-6, 6-3, ret. victory.

Parmentier had just leveled the match at one set apiece when Wozniacki, who had earlier received an off-court medical timeout, elected not to continue, truncating the match after 94 minutes and sending Parmentier into her first WTA semifinal of the 2018 season.

Parmentier converted five of her six break points in the match, and had 14 winners, five more than Wozniacki. Nevertheless, the players were not separated by much while the match was in progress, as Parmentier won only one more point than Wozniacki before the top seed was forced to retire.

"It's a good win today, but I saw she had some problems in the second set with the serve. She was not serving full speed. It's tough when you see your opponent not doing well," Parmentier said after the match.

"Even though we are opponents on the court, we want everyone to be fine, so it's not easy."

Parmentier started the match by breaking Wozniacki’s serve, before the Dane reeled off four straight games to lead 4-1. But Parmentier was unfazed by the winning streak, quickly holding for 4-2, and then getting back on serve at 4-3 when Wozniacki double faulted while down break point.

A backhand winner off of the netcord gave Parmentier her third straight game, leveling the match at 4-4. But Wozniacki would come through in the final stages of the set, holding for 5-4 with solid play off the forehand side, and then breaking Parmentier for a one-set lead via a forehand winner off of the heavily involved netcord.

Wozniacki edged her way to the one-set lead with one more winner than Parmentier in the opener, six to five. Parmentier also had 16 unforced errors, while Wozniacki had only 10 miscues. Wozniacki put nearly 80 percent of her first serves in play as well.

Parmentier, though, still had designs on taking her first victory over the reigning Australian Open champion. The Frenchwoman broke in the first game of the second set behind a winning drop volley, and then claimed a 3-0, double-break advantage by forcing a Wozniacki error with a strong forehand.

At this juncture, Wozniacki took an off-court medical timeout, but, upon resumption, Parmentier stayed on track, easily holding for 4-0. Wozniacki finally got on the board at 4-1, but Parmentier pressed on, reaching 5-2 and a chance to serve for the set.

It was only here where the Frenchwoman faltered, dropping serve as Wozniacki added more depth to her shots, pushing Parmentier back into the court and drawing errors. But the top seed failed to keep momentum from that break of serve, double faulting to give Parmentier double set point. A backhand error tied the match at one set all, and Wozniacki decided to call it quits for the day.

The unseeded Frenchwoman will now face either No.7 seed Irina-Camelia Begu of Romania or unseeded Donna Vekic of Croatia in the final four in Istanbul. The other semifinal will be between two unseeded players, Polona Hercog of Slovenia and Maria Sakkari of Greece.

"I was practicing really hard durind the Fed Cup week. I also did two good matches last weekend, even if I lost the matches. I found some confidence there even if I lost," the Frenchwoman said, referencing a pair inspired efforts she gave against Americans Sloane Stephens and Madison Keys in the Fed Cup semifinals.

"I really like to play on clay and even if I was not playing good at the beginning of the year, I almost forgot it because I was feeling good on clay as soon as I went on the court. It's good to win a few matches here and to feel good for the next few weeks."