Russia’s Medvedev had reached the final at the Australian Open for the past two years but could not match Korda’s level on Rod Laver Arena.
“I think it was a top match where he was just better than me,” said Medvedev, who lost his last four matches of 2022.
“I won many matches like this. Right now, I’m struggling a little bit to win these kind of matches against opponents that can play a good level.
“That’s what I have to find back.”
Korda is through to the fourth round in Melbourne for the first time, following the footsteps of his father, Petr, who won the tournament in 1998.
His mother Regina Rajchrtova was also a professional tennis player, while his sisters Jessica and Nelly are LPGA golfers.
“My family loves playing Australia, we’ve got a lot of awesome moments here,” said Korda, who is ranked 31st in the world.
“Both of my sisters have won the Australian Open in women’s golf. My mum’s career-high [ranking] was 24, my dad was two, Nelly was one and Jessica was six so I’m definitely the worst athlete in the family so far.”
Korda will play Poland’s Hubert Hurkacz in the fourth round after the 10th seed reached that stage of the tournament for the first time with a hard-fought 7-6 (7-3) 6-4 1-6 4-6 6-3 victory over Denis Shapovalov of Canada.
Tsitsipas continues strong start
Earlier on Friday, Tsitsipas continued his strong start to the tournament with a straight-set win over Tallon Griekspoor to reach the fourth round.
The Greek is yet to drop a set in Melbourne as he bids for his first Grand Slam title and beat the 63rd-ranked Dutchman 6-2 7-6 (7-5) 6-3.
He will face Jannik Sinner next after the Italian fought back from two sets down to beat Marton Fucsovics.
Sinner, seeded 15th, came through 4-6 4-6 6-1 6-2 6-0 against Hungary’s Fucsovics.
It is the first time in his career that he has come back from two sets down to win at a Grand Slam.
Sixth seed Felix Auger-Aliassime beat Francisco Cerundolo 6-1 3-6 6-1 6-4 to set up a meeting with rising Czech star Jiri Lehecka, who beat Britain’s Cameron Norrie.
After his win, Auger-Aliassime addressed a ‘Netflix curse’, which is supposedly causing players who featured in the recently released series Break Point to bow out of the Australian Open early.
Casper Ruud, Ons Jabeur, Maria Sakkari, Matteo Berrettini, Taylor Fritz and Thanasi Kokkinakis are all out, while Nick Kyrgios, Paula Badosa and Ajla Tomljanovic had to withdraw before the tournament began.
“I thought it was funny,” Auger-Aliassime said.
“I don’t know. I don’t think it’s connected. Maybe the players that lost, maybe they do feel like it’s connected somehow. I don’t think they do.”
Karen Khachanov made it to the Australian Open fourth round for the first time with a 6-3 6-4 3-6 7-6 (11-9) win against American Frances Tiafoe – and apologised for potentially ruining a special day.
Khachanov said after the win: “I know it is Frances’ birthday, so I am sorry!”