Serena Williams said she would "love" to test herself against world number one Simona Halep, though the seven-time Australian Open champion is rooting for sister Venus.

Williams stormed into the round of 16 at Melbourne Park after overpowering 18-year-old Ukrainian Dayana Yastremska 6-2 6-1 on Saturday.

The 23-time grand slam champion will face the winner of Halep and sibling Venus Williams for a spot in the quarter-finals.

Williams has not faced the WTA's top-ranked player since returning from the birth of her daughter last year.

Asked if a meeting with Halep would prove where her game is, 16th seed Williams told reporters: "I honestly would love to face the world number one."

"At the same time I would love for Venus to win. I think either way, regardless, I'll be ready for either opponent."

"It will be great. I haven't played the world number one since I've been back. So, yeah, it will be good."

Serena Williams and older sister Venus have not met since last year's US Open, where the former triumphed in straight sets to move into the quarter-finals.

The 2017 Australian Open also saw Serena beat Venus in the women's final.

Asked about the prospect of an all-Williams fourth-round encounter, Serena said: "We're really close. She's even closer to [daughter] Olympia. She's more than an aunt, but she's not the mom. She's, like, the stage after that."

"She's so close to being there with my daughter, so we talk all the time, spend a ton of time together. She gives me tips and stuff. We'll definitely be talking, take it as it is. Take it one step at the same time."