Djokovic's quest for a 100th career title bit the red dust on Wednesday, the 24-time grand slam champ being handed another surprising loss, 6-3 6-4, at the hands of Chilean Alejandro Tabilo, who also beat the great man in Rome last year.
It was such a sub-standard performance in his first clay-court outing since winning the Olympics that Djokovic could only sound embarrassed as he sighed to the crowd on Court Rainier III: "I expected myself at least to have put in a decent performance. Not like this. It was horrible.
"I did not have high expectations. I knew I'm going to have a tough opponent and I knew I'm going to probably play pretty bad. But this bad, I didn't expect."
Yet in the first major European clay-court event of the post-Rafa Nadal era, both de Minaur and Popyrin offered glimpses they could enjoy their best seasons yet on the surface as they came from a set down in their matches to book last-16 places.
In the year after de Minaur finally began to feel like a clay-courter by reaching the French Open quarter-finals, Australia's world No.10 produced an emphatic comeback to subdue Czech Tomas Machac 3-6 6-0 6-3.
Based on his fine returning grinding down the Czech, de Minaur's win set up the eighth seed with a round-of-16 date against ninth seed Daniil Medvedev, who came through a testing encounter with Frenchman Alexandre Muller 7-6 (8-6) 5-7 6-2.
It will be 'Demon's' first encounter with Medvedev since the Aussie got beaten in last year's ATP Finals, but he'll be keen to repeat his shock victory over the Russian at Roland Garros which earned him his first French Open last-eight berth.
De Minaur had been scheduled to potentially meet Djokovic in the quarter-finals, but it's back to the drawing board for the Serb, who had looked a bit more like his old self in last month's Miami Open before being beaten in the final by teenager Jakub Mensik. Â
Popyrin has had a poor season following his breakthrough 2024 campaign, but there were signs of real promise from the former Roland Garros boys' champ that a decent clay-court campaign awaits as he won his second match in two days from a set down, 3-6 6-3 6-3, against US 14th seed Frances Tiafoe.
It gave the 25-year-old Sydneysider, who blasted 27 winners, a measure of revenge for his defeat by Tiafoe in last year's US Open.
It's also the first tournament in 2025 in which Popyrin has won two matches, after going into Monte Carlo with a dismal 2-7 record.
A real measure of his improvement, though, may now await when he faces fourth seed, two-time French Open finalist Casper Ruud, in the last-16 after the Norwegian hammered Roberto Bautista Agut 6-2 6-1.
French Open champion Carlos Alcaraz began his clay campaign which he hopes will lead to a successful French Open title defence by rallying to a 3-6 6-0 6-1 victory over Argentine world No.22 Francisco Cerundolo.
There was also plenty of emotion as Monte Carlo said farewell to French favourite Richard Gasquet, playing his last event there a quarter-of-a-century since he played in Monte Carlo as a 15-year-old wildcard. At 38, he lost to German qualifier Daniel Altmaier 7-5 5-7 6-2.
