Third seed Stefanos Tsitsipas earned a straight-sets victory over Frenchman Quentin Halys to reach the second round of the Australian Open.
The Greek, who has yet to lose a game this year, won 6-3 6-4 7-6 (8-6) on matchday one at Melbourne Park.
The three-time semi-finalist will face Australian Rinky Hijikata, who came on after two sets to beat qualifier Yannick Hanfmann, next.
Seventh seed Daniil Medvedev will face American Marcos Giron later on Monday.
“It was tough, he found some good tennis in the third set, I kind of lost my rhythm on serve,” Tsitsipas said.
“So I had to find ways to get out of this difficult situation. I think my fighting spirit came through towards the end, I wasn’t going to give up.”
Elsewhere in the gentlemen’s singles, teenager Shang Juncheng became the first male Chinese player to win an Australian Open main draw singles match.
The 17-year-old qualifier, the youngest player on the men’s roster, beat Germany’s Oscar Otte 6-2 6-4 6-7 (2-7) 7-5.
“I think it’s huge for Chinese men’s tennis. We had some really good players on the women’s side but not really big names on the men’s side,” Shang said.
He will face Frances Tiafoe after the 16th seeded USA beat Germany’s Daniel Altmaier 6-3 6-3 6-7 (5-7) 7-6 (7-8).
Tiafoe’s kit – a pink, blue and red wavy number – has divided opinion on social media, with one user commenting that the outfit “deserves to reach the second week minimum”.
former champ Stan Wawrinka fell in the first round, the Swiss losing 6-7 (3-7) 6-3 1-6 7-6 (7-2) 6-4 against Slovakian Alex Molcan.
American Wildcard Christopher Eubanks defeated the in-form Kwon Soon-woo in five sets to claim his first main draw victory in Melbourne.
Meanwhile, Poland’s tenth seed Hubert Hurkacz overtook Spaniard Pedro Martinez in straight sets when seeded sixth Felix Auger-Aliassime overcame a poor first set to beat fellow Canadian Vasek Pospisil 1-6 7-6 (7-4) 7-6 (7-3) 6-3.