ROME, Italy - Unseeded Victoria Azarenka earned a berth in the quarterfinals of the Internazionali BNL d'Italia on Friday when Daria Kasatkina retired due to a right ankle injury she sustained in the first-set tiebreak. 

As the Russian chased a ball that clipped off the net on the second point of the tiebreak, with Azarenka leading 1-0, she rolled over on her right foot as she slid in an attempt to reach the ball.

After an emotional scene in which she was comforted by Azarenka on the court, the Russian was unable to continue and retired from the match after one hour and 16 minutes of play.

"I'm really sad for Daria because we were playing such great tennis. I felt it was such a great fight and she's such a talented player... and I felt like this was maybe closer to being her moment, so it's very unfortunate that she has an injury," Azarenka said after the match.

"It's difficult to find the words when you have emotions. I know how sad she was, and I could see that she worked really, really hard... and she was very gracious that my, kind of, 'comeback' has inspired her and I just told her to keep going. She's a strong girl and she has a big personality, so I think she'll be fine."

Over the course of the first 12 games, the two players traded breaks four times. After the Belarusian led 3-1, Kasatkina won three straight games to move a break ahead herself, and later was broken serving for the set twice at 5-4 and 6-5. 

"She was playing so beautifully, so smart on the court, putting me in very uncomfortable situations where I really had to push myself," Azarenka added. "It was a really great battle out there and I was enjoying it a lot.

"It was a lot of rallies, there were a lot of tactics going on on the court. I think that what I would take for myself... was that I was just talking a little bit too much, not necessarily negative, just too much.

"At 6-5, I felt like I was getting into a better rhythm... and I felt like I was finding the quiet space for myself to maybe step up a little bit to another level. I don't know if it would've happened, but that's how I felt."

Azarenka advances to a quarterfinal meeting Garbiñe Muguruza, who saw off 2019 finalist Johanna Konta in straight sets in a near-simultaneous finish. Last year, the Belarusian won their third-round clash via retirement when she was leading Muguruza, 6-4, 3-1. 

"My next match is going to be very different from today, so I don't think that I can take that much from today," Azarenka said.

"In terms of what I can do, I have to focus on my game. I think that's what I do best, when I focus on my game and imposing my way of playing. Obviously, [there's] adjusting a little bit because of the clay, and bring a little more variety this time, but I don't really expect tomorrow to have long rallies like today.

"I'll have to adjust again to a different ball but I'm actually very excited about this match. We played last year and it was a good match.

"She's been playing great. I watched a little bit of her against Coco Gauff, which was a great match. It's going to be a great battle and I'm sure it's going to be fun."

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