MIAMI, FL, USA - For the first time in four career meetings, Venus Williams was a straight-sets victor over Daria Kasatkina on Sunday.

Williams soared into the last 16 at the Miami Open for the fourth time in the past five years with a 6-3, 6-1 win over the No.14 seed in third-round action.

The seven-time Grand Slam champion broke the Russian's serve eight times in the match, losing just one game after trailing 3-2 in the opening set.

"I think in a lot of the matches we played before, she was just on top of her game, couldn't miss. I think today I was just able to control the points. I got a few more errors," Williams said.

"I'm always at my best when I'm playing aggressive. I just got to execute that today."

Both players needed time to adjust on serve over the course of the first set, as the match opened with six straight breaks, before Williams recorded the first hold in the seventh game. 

The former World No.1 rounded into form against her Russian rival from then on, as she lost just two points over the last three games of the first set, and nearly ran off the last nine games of the match in total.

Kasatkina finally got on the scoreboard with a break as Williams served for a bagel, but the struggles that plagued her for one hour and 15 minutes continued in the final game as she dropped serve for the sixth and final time.

"I didn't realize that [she broke serve in every game] until after the match looking at the stats. I've never had a match before like that in my life. There's always a time for a first," Williams assessed.

"I'm returning really well. 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-off against No.2 seed Simona Halep for the seventh time, and second time this season.

The Romanian scored a 6-2, 6-3 victory in the third round of the Australian Open, and the pair's head-to-head is level at 3-3 as Halep has won three straight.

"She always plays flawless tennis against me, so I have to be ready for that," the American said.

"Every match is a different match, opportunity to play better and to learn. I know each point will be an opportunity for me to play better and learn. That's how I look at it. I'm looking forward to tomorrow."