An emotional Alexei Popyrin said he always believed he could beat the best after the 113th-ranked local hope stunned eighth seed Taylor Fritz at the Australian Open on Thursday.
American Fritz, who had a breakthrough 2022 with titles at Indian Wells, Tokyo and Eastbourne, fell in five gruelling sets at a partisan John Cain Arena.
Australia's Popyrin, a wildcard at the tournament, prevailed 6-7 (4/7), 7-6 (7/2), 6-4, 6-7 (6/8), 6-2.
The opening Grand Slam of the year has now lost three of its top 10 seeds before the third round, with Rafael Nadal and Casper Ruud also crashing out early.
"This is a dream and I don't want to wake up at all," said Popyrin, 23, who equalled his best Grand Slam result and was reduced to tears by the crowd chanting his name.
"Pre-season I put my head down and worked as hard as I possibly could... I'm going to keep working. I love this feeling and I want more of this feeling."
Fritz, who helped spearhead the US to the United Cup title leading into the Australian Open, had never before lost at Melbourne Park to a player ranked as low as Popyrin.
"From the start, honestly, I have that confidence going into every match. I think I have the game to beat the guys at the top," said the Australian.
"Done that twice already this year. Beat two top-10 guys," he added, having swept past Canada's Felix Auger-Aliassime in Adelaide this month.
"For me it's very important going into that match knowing I have that confidence, knowing I have the game to beat them, which I truly believe that I do.
"It's huge to back up talk. I think it's important to back up talk."
He will play another American next in Ben Shelton, who came through against Chile's Nicolas Jarry in straight sets.