Elena Rybakina says she will need some "magic" if she is to go deep at the Australian Open after struggling with a back problem in her third-round win.

Sixth seed Rybakina, runner-up at Melbourne Park two years ago, beat Ukraine's Dayana Yastremska 6-3 6-4 but needed a medical timeout after just three games.

The 25-year-old Kazakh was visibly struggling to move and needed seven match points to close out victory.

Asked afterwards if her back was OK, Rybakina replied: "Not really. I will see my physio and hopefully he does some magic.

"It's not so good since it's [my] lower back. Hopefully we can do everything possible.

"But for now it doesn't seem too good, to be honest."

Former Wimbledon champion Rybakina had a number of injury problems in 2024, struggling at various points with fatigue, illness and a back issue.

Against Yastremska, Rybakina tried to shorten the rallies and hit winners in an attempt to speed up the match - helped in part by 37 unforced errors from her opponent.

"I needed to stay there and try to hold my serve," Rybakina said.

"I knew that it would be very difficult for me to stay long in the rally so I was trying sometimes risk a little bit more."

Rybakina will face either Danielle Collins or Madison Keys, who play later on Saturday, in the fourth round on Monday.

American eighth seed Emma Navarro joked she "can't resist" going the distance in her matches after winning her third consecutive three-set encounter at Melbourne Park.

The 23-year-old beat former Wimbledon and US Open finalist Ons Jabeur 6-4 3-6 6-4 to reach the fourth round.

Since the start of 2024, Navarro has played 32 matches that have gone the full three sets, winning 23 of them.

"I love three sets. I love tennis so much I can't resist, I gotta play three sets," Navarro said.

Navarro is the daughter of billionaire businessman Ben Navarro, founder of the Sherman Financial Group, and credited her dad for her stamina, saying he would take her and her siblings on six-hour bike rides as youngsters.

"We made up a term: biking and crying," Navarro said.

"I learned a lot of toughness growing up. A lot of thanks goes to him."

Navarro will play Russian ninth seed Daria Kasatkina, who beat Kazakh Yulia Putintseva 7-5 6-1, next.