ROME, Italy - Victoria Azarenka and Garbiñe Muguruza's rivalry continues to be dogged by ill fortune: for the second time this year, a clash of the former World No.1s ended in retirement, this time when Muguruza called it quits trailing 6-4, 3-1 in the third round of the Internazionali BNL d'Italia due to a left thigh injury.

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The last time the pair had met, in the Monterrey final last month, it had been Azarenka who had limped off court suffering a leg injury while trailing 6-1, 3-1. Today, though, the two-time Australian Open champion was fresh and playing her first match - while Muguruza had already spent two hours and eight minutes on court earlier to notch up a three-set second-round win over Danielle Collins.

Nonetheless, the 25-year-old would contribute her fair share of impressive tennis to a tight 49-minute first set in which both players struck the ball cleanly off the ground. Indeed, there would be just one break point throughout - and, set up by Azarenka in the seventh game with a blitzed backhand winner and converted with an aggressive return, it would prove decisive. Conceding only seven points behind her own delivery in the opening set, the 2013 runner-up was particularly sharp in ending points with her forehand, and twice closed out a hold with an ace.

Muguruza was notably less effective on serve, landing just 53% of her first deliveries compared to Azarenka's 61% - and crucially appeared to be feeling the effects of her earlier match. Indicating an issue with her thigh to the physio, she took an off-court medical timeout leading 2-1.

Stuttgart quarterfinalist Azarenka did not hesitate to test Muguruza's movement, running the former Roland Garros champion side to side and up and down with her heavy groundstrokes and pouncing on any short ball. A magnificent return set the Belarusian up to break Muguruza from 40-0 up in the third game of the second set, with a wayward drive volley sealing the game for Azarenka - and a pair of backhand winners down the line to hold for 3-1 would be the final nail in the coffin as the Spaniard conceded defeat thereafter.

Azarenka thus moves into the last eight of Rome for the fifth time in her career, having been runner-up to Serena Williams in 2013, semifinalist in 2009 and quarterfinalist in 2011 and 2015 - and will await either No.4 seed Karolina Pliskova or Sofia Kenin in a bid to reach her first Premier semifinal since Miami 2018.