Carlos Alcaraz has Novak Djokovic demanding payment after powering into the Australian Open quarter-finals on Sunday as Aryna Sabalenka set up a showdown against one of the brightest talents in tennis.
Top seed Alcaraz was in ominous touch at Rod Laver Arena, dismissing the American Tommy Paul 7-6 (8/6), 6-4, 7-5 in a masterclass.
The 22-year-old Spaniard plays home hope and sixth seed Alex de Minaur or 10th seed Alexander Bublik of Kazakhstan next.
Alcaraz, who is yet to drop a set at this year's tournament, has never gone beyond the quarter-finals in Melbourne.
If he can finally break his Australian duck he will become the youngest man in history to win a career Grand Slam of all four majors.
Alcaraz has in the past struggled with precision and a lack of consistency in his serving technique.
He is now sporting a new-look serve that has become a handy weapon - and been compared to Djokovic's serve.
"I had a Djokovic message saying, 'you have to pay me'," he said in his on-court interview after making light work of 19th seed Paul, to laughter from an adoring crowd.
Later, three-time finalist Daniil Medvedev could face another marathon against up-and-coming American Learner Tien.
Tien and former number one Medvedev met three times last year, with the younger man winning twice, including a five-setter in the second round of the Australian Open.
"Will try to do my best to maybe surprise him somewhere," said Medvedev, from Russia.
Whoever comes out on top will face third seed Alexander Zverev of Germany or Francisco Cerundolo of Argentina.
World number one Sabalenka will face impressive 18-year-old American Iva Jovic in a tasty last-eight encounter.
Belarusian top seed Sabalenka, a two-time Melbourne champion, opened the day on Rod Laver Arena and saw off the brave challenge of 19-year-old Canadian Victoria Mboko.
Sabalenka won 6-1, 7-6 (7/1) while Jovic destroyed unseeded Yulia Putintseva 6-0, 6-1 in just 53 dominant minutes.
"What an incredible player for such a young age," said Sabalenka of the 17th-seeded Canadian Mboko, who has emerged as a serious threat in the past year.
"I feel like I am a kid still! She pushed me really hard today and played incredible tennis."
Sabalenka raced through the second-set tiebreak - the 20th Grand Slam tiebreak in a row she has won - to seal victory.
She has yet to drop a set as her title charge gathers pace.
But in Jovic, who only turned 18 last month, she clashes with a player in red-hot form and rising fast, now ranked 27 having been 191 this time last year.
Jovic, who stunned two-time Grand Slam finalist and seventh seed Jasmine Paolini in the third round, said: "I feel great. I'm really glad to get through."
Jovic is the youngest player to reach the women's quarter-finals at the Australian Open without dropping a set since Venus Williams in 1998.
Third-seeded American Gauff faces Ukraine's Elina Svitolina or another 18-year-old, Russian Mirra Andreeva, in the quarter-finals.
Gauff dropped a set for the second match in a row before clawing her way past Karolina Muchova 6-1, 3-6, 6-3.
The 21-year-old Gauff, a two-time major champion, has never gone beyond the last four at Melbourne Park.
