Serena consoles Ukrainian teen, Djokovic sees off Shapovalov

Serena Williams powered into the fourth round of the Australian Open on Saturday with a 6-2 6-1 demolition of Dayana Yastremska then consoled the Ukrainian teenager after leaving her in tears.

The 37-year-old Williams, chasing a record-extending eighth Melbourne title in the professional era, barely broke sweat on a sunny afternoon at Rod Laver Arena as she racked up 20 winners and beat the 57th-ranked 18-year-old in a breezy 67 minutes.

"As she was walking towards the net, I could tell she was quite upset," Williams told reporters. "I kind of liked that. It shows she wasn't just there to play a good match, she was there to win. She wanted to win. That really broke my heart.

"I think she's a good talent. It's good to see that attitude."

Yastremska rolled her right ankle midway through the match and took a medical time-out to have her foot bandaged when trailing 4-1 in the second set.

It stalled defeat only briefly, however, as Williams broke her a third time in the set and claimed the match when the Ukrainian sprayed a cross-court forehand wide.

Chasing her 24th Grand Slam title, Williams has conceded only nine games at the tournament and not dropped a set but may finally have a test when she plays the fourth round.

She will face the winner of older sister Venus and top seed Simona Halep for a place in the quarter-finals.

She mentioned Venus was one of the players that left her crying after defeat.

"I remember one time in particular against Venus at Wimbledon, as I was walking to the net, I started bawling," she said. "I couldn't help it. Young girls, young women, just want to go out there and do their best and want to win."

Since returning to the tour after maternity leave, Williams has yet to win a Grand Slam as a mother after two near-misses in the finals at Wimbledon and the U.S. Open.

Seeded 16th in Melbourne, she felt torn about who she might like to play next but said a match against top seed Halep would test her true level.

"Yeah, and I honestly would love to face the world number one," she added.

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

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

Angry Djokovic regains calm to see off Shapovalov challenge

Top seed Novak Djokovic regained his composure after a third-set meltdown to stave off the challenge of Canadian teenager Denis Shapovalov and reach the fourth round of the Australian Open with a 6-3 6-4 4-6 6-0 victory on Saturday.

The 14-time Grand Slam winner stamped his authority early on by breaking the 19-year-old's serve three times and converted his only breakpoint opportunity in the second set while leading 5-4 to take a 2-0 lead.

The 31-year-old lost his cool in the third set, however, after his request to turn off the artificial lights was ignored and he muttered to himself angrily and before losing two consecutive break of serves to concede the set.

The Serb let out his frustration with a huge roar when he broke Shapovalov early in the fourth, though, and romped through the rest of the set to remain on course for an unprecedented seventh title at Melbourne Park.

The reigning Wimbledon and U.S. Open champion will next meet Russian 15th seed Daniil Medvedev, who notched up his best Grand Slam showing till date by reaching the fourth round with a 6-2 7-6(3) 6-3 win over David Goffin of Belgium earlier in the day.

Nishikori silences Portuguese fans with Sousa rout

Japan's Kei Nishikori moved swiftly into the fourth round of the Australian Open on Saturday after beating Joao Sousa of Portugal 7-6(6) 6-1 6-2.

The comfortable victory came as a relief to the eighth seed and former U.S. Open finalist after he battled through consecutive five-set matches in the opening rounds.

"I think today will help," the three-times quarter-finalist said after setting up a clash with Spain's 23rd seed Pablo Carreno Busta.

Both Nishikori and Sousa entered their match after tight opening rounds and were evenly matched in the early exchanges on their favoured hard court surfaces.

But after a close tiebreaker, Nishikori took near total control, increasing the pace on his ground strokes and showing soft hands at the net; a quality his opponent couldn't replicate.

He said he would continue attacking the net after using the tactic successfully on Saturday.

"I think third set, I started coming (in) a little more, I think that was working well," said Nishikori.

A small pocket of red and green-clad fans added a football-like atmosphere to the clash as they cheered Portugal's top-ranked player.

But Nishikori robbed them of their voice, as he unleashed forehand winners almost at will, a stroke he said was his favourite shot despite being better known for his double-handed backhand.

Fittingly, the Michael Chang-coached Nishikori ended the contest with a clean, cross-court forehand winner to keep his hopes of a maiden Grand Slam alive.