ABU DHABI, U.A.E. -- No.1 seed Sofia Kenin of the United States moved into the third round of the Abu Dhabi WTA Women’s Tennis Open on Friday afternoon after Belgium's Kirsten Flipkens had to retire at 5-7, 5-4, due to a left ankle injury which occurred during the match.

"I obviously got a little bit upset, emotional," Kenin told the media, after the match ended. "We’re good friends and that’s not something you like to see. I just hope [Flipkens] can have a speedy recovery and get ready for Australia."

The third meeting between the two players had been very competitive, with 86th-ranked Flipkens winning a set off of World No.4 Kenin for the first time in their rivalry. There had been five service breaks by each player during the affair, and only two winners separated the pair (19 for Kenin and 17 for Flipkens).

Kenin had moved ahead by a break in the second set and was serving to level the match at one set apiece when Flipkens, a former Top 20 player and 2013 Wimbledon semifinalist, suffered her unfortunate injury.

"She played a really good match," Kenin said. "It was the third time we’ve played each other, and it was a really solid match from both of us. This is not the way I wanted to win."

"I just hope she’s going to have a speedy recovery, she’s obviously playing well," Kenin added. "This is just really unfortunate, and I’ll write to her later tonight, asking how she is."

A flurry of breaks at the start of the match came to an end with Kenin holding for 3-1, as the top seed grasped the early lead. However, Flipkens quickly moved back to level footing, firing a forehand crosscourt return winner to break the American once more and reach 3-3.

All-court play was the order of the day throughout the first set, with both players putting away points in the forecourt as they traded breaks again en route to 4-4. A tremendous tussle took place in the ninth game, which went through three deuces until Kenin claimed another break by cracking open a rally with an error-forcing forehand to lead 5-4.

After that battle, though, Flipkens ended up winning the first-set war. The Belgian would claim 12 points in a row from there, as Kenin dropped her serve at love twice consecutively. Flipkens completed her stunning three-game run with another forehand crosscourt return winner, taking the topsy-turvy opening set with a final flourish.

Once the second set began, though, Kenin amped up the aggression. The top seed had two break points in the opening game of the set, and though the American could not convert either of those chances, she had another look on the Belgian’s serve at 2-2. Dominating with her backhand in that game, Kenin broke for 3-2 to eke ahead in the second set.

"I obviously didn’t finish off the first set so good, but, of course, she picked up her game and played some really good points," said Kenin. "I just tried to keep fighting. The momentum wasn’t going my way so much into the second, so I tried to hang in there."

"Things started turning around for me and I started playing better, and then, unfortunately, the whole incident changed everything," the American continued.

Flipkens did well to prevent herself from going down a second break, saving another of Kenin's chances at 4-2 by putting away a winning volley. The Belgian continued to strike the ball with force as she held on for 4-3, but Kenin kept zoning on her backhand side while maintaining her lead, putting herself a game away from leveling the encounter at one set all.

Flipkens held for 5-4 with an ace, but Kenin was now on the brink of serving out the second set. Unfortunately, during the second point of the game, Flipkens injured her left ankle. The Belgian was treated in her chair by medical staff, but she was unable to continue the clash.

2020 WTA Player of the Year Kenin, the reigning Australian Open champion, will now face No.13 seed Yulia Putintseva in the round of 16. Putintseva of Kazakhstan defeated Barbora Krejcikova of the Czech Republic in straight sets on Friday.

Kenin previews 2021 start in Abu Dhabi