A day after her sister withdrew from the tournament with a knee injury, Venus Williams moved on to the Round of 16 of the Miami Open after beating 14th-seeded Russian Daria Kasatkina 6-3, 6-1 on Sunday.
Williams needed just 74 minutes to clinch victory, as Kasatkina struggled mightily with her serve. She had six double faults and won just 17 of 54 points on her own service, failing to win a single service game. Williams converted all eight of her break-point opportunities.
"I didn't realize that [she broke serve in every game] until after the match looking at the stats," Williams said afterward, per WTA.com. "I've never had a match before like that in my life. There's always a time for a first."
Williams had her own issues serving, as she was broken on each of her first three service games, including a 19-point slog in the third game. But she stabilized in the second set, allowing just one break.
"I'm returning really well," Williams said. "If I'm getting a look at the serve, it's going well for me. I want to return that well tomorrow, too."
Williams will next face second-seeded Romanian and former world No. 1 Simona Halep, who battled back to down Slovenia's Polona Hercog 5-7, 7-6 (1), 6-2 on Sunday. Williams and Halep have met six times before, splitting the matches 3-3, most recently with a straight-sets victory from Halep at the Australian Open.
In Sunday's final match, fourth seed and defending champion Sloane Stephens was ousted by Germany's Tatjana Maria 6-3, 6-2.
Maria broke Stephens five times, including three times in four service games in the second set. She ultimately put the match away on her fourth match point, the 13th point of the eighth game of the set.
"I could not be happier right now," Maria said in an on-court interview after winning. "I think I played at home, because I live here. It was helping me a lot.
"My game is pretty special, so I knew that tonight I had a chance. I played two times against Sloane, so I knew what to expect."
In other seeded action, No. 5 Czech Karolina Pliskova avoided an upset, recovering to beat Frenchwoman Alize Cornet 6-7 (3), 6-1, 6-4.
Latvian 11th seed Anastasija Sevastova wasn't as fortunate, blowing an early advantage to lose 1-6, 6-2, 6-3 to Yulia Putintseva of Kazakhstan. Also losing were Belgian 16th seed Elise Mertens -- 6-4, 7-6 (1) to Czech Marketa Vondrousova -- and American 25th seed Danielle Collins, who fell 7-5, 6-1 to China's Yafan Wang.
--Field Level Media