Two-time runner-up Daniil Medvedev reached the second round of the Australian Open with a straight-set win over American Marcos Giron.

"Great memories of last year, but I want to have better ones this year," Medvedev, who lost to Rafael Nadal in last year's final, said.

Third seed Stefanos Tsitsipas also advanced on the opening day's play at Melbourne Park.

Medvedev lost just three games against Giron - the fewest he has ever dropped in a Grand Slam match.

Greece's Tsitsipas, a three-time semi-finalist in Melbourne, beat France's Quentin Halys 6-3 6-4 7-6 (8-6).

He will face Australia's Rinky Hijikata next while 2021 US Open champion Medvedev will take on John Millmannext.

"It was challenging, he came up with some good tennis in the third set, I kind of lost my rhythm in the serve," said Tsitsipas.

"So I had to find ways to get out of the difficult situation. I think my fighting spirit showed towards the end, I wasn't going to give up."

Elsewhere in the men'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 in the men's draw, 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 have had really good players from the women's side but not really big names in the men's," said Shang.

He will face Frances Tiafoe after the American 16th seed beat Germany's Daniel Altmaier 6-3 6-3 6-7 (5-7) 7-6 (7-8).

Tiafoe's kit - a squiggly pink, blue and red number - divided opinion on social media, with one user commenting the outfit "deserves to get to the second week minimum".

Former champion Stan Wawrinka fell in the opening round, with the Swiss losing 6-7 (3-7) 6-3 1-6 7-6 (7-2) 6-4 to Slovak Alex Molcan.

American wildcard Christopher Eubanks beat the in-form Kwon Soon-woo over five sets to claim his first main-draw win in Melbourne.

Meanwhile, Polish 10th seed Hubert Hurkacz cruised past Spaniard Pedro Martinez in straight sets and sixth seed Felix Auger-Aliassime overcame a poor first set to beat Canadian compatriot Vasek Pospisil 1-6 7-6 (7-4) 7-6 (7-3) 6-3.