Rublev will compete against either Australian hopeful Alex De Minaur or nine-time champion Novak Djokovic, who is struggling with a hamstring injury.
In a tense five-set match on Monday, fifth seed Andrey Rublev defeated Danish teen Holger Rune and earned a spot in the Australian Open quarterfinals by saving two match points.
The Russian won 6-3, 3-6, 6-3, 4-6, 7-6 (11/9) in stifling heat at Rod Laver Arena in a battle between two former junior world number one players.
He broke when Rune was serving for the match, saved two match points, and then won the match. He will compete against either Australian hopeful Alex De Minaur or nine-time champion Novak Djokovic, who is struggling with a hamstring injury.
The 25-year-old advanced to the Melbourne quarterfinals for the second time, making it his seventh Grand Slam appearance. Rublev, who has won 13 ATP titles and is ranked sixth in the world, has never advanced.
Rublev broke the Dane with a forehand winner to take a 4-2 lead in the first set, despite the fact that both players were serving less-than-clinically.
But Rune made chances with his returns, and when Rublev played into the net from the baseline, he immediately responded.
Rublev served out the set in 37 minutes this time, making no mistakes after his opponent took advantage of a Rune double fault.
Rune refused to give up in a 12-minute opening game of set two and turned the tables on Rublev to break him for a 3-1 lead that he never gave up.
Rublev pounced in the sixth game of the following set as the sun was setting, creating three break-point opportunities that he capitalized on.
Rune called a trainer for what appeared to be a blood pressure test when he was down two sets to one. Unperturbed, he got back to work and broke for 4-2 and extended the match to a fifth.
Rune defeated Rublev in a battle of attrition to move to 5-2 in the decider, but he failed to serve out the match.
After that, Rublev saved two match points to advance to the 10-point tiebreaker, where he overcame a 7-3 deficit to win bravely.