Alex de Minaur’s gloomy grand slam ordeals have materialised once more in the Paris sunshine.

Australia’s main man has been knocked out of the French Open just when opportunity had knocked deafeningly for all the would-be contenders.

With Jannik Sinner’s sensational exit having made everyone believe their chance could be at hand, de Minaur’s enduring dream was this time dynamited by young Czech powerhouse Jakub Mensik 0-6 6-2 6-2 6-3 in the third round.

For a 20-year-old who’d collapsed on court and had to be ferried to the medical centre in a wheelchair after his four-hour 41-minute epic win over Mariano Navone just two days earlier, Mensik was outrageously good, rebounding from a horror opening set to utterly dominate.

Jakub Mensik of the Czech Republic during the match against de Minaur. Photo: AAP

The continuing hot, sticky conditions on Roland Garros’s lovely greenhouse Court Simonne Mathieu looked sure to benefit de Minaur, as it felt almost unimaginable that the figure who’d been at the centre of such alarming scenes on Wednesday, unable to get up off the clay for several minutes, should look so comfortable.

Not to start with, though. In an extraordinary opening, the rested de Minaur, with only one three-set match in his legs all week following his second-round walkover, began like a demon.

He kicked off with an immediate break and went on an extraordinary run of 16-straight points with the Czech, a step off the pace and sluggish, coughing up 11 errors as he won just five points in the entire 19-minute first-set ‘bagelling’.

Thoughts may already have been turning towards the prospect of a last-16 meeting with Andrey Rublev, such was the Australian’s mastery.

But as if the Czech had enjoyed the changeover in a telephone box, he re-emerged super-charged, hitting more cleanly, scuttling around more convincingly to win a 21-stroke point to help earn a second-game break. He started to bully the Australian with his superior power and accuracy.

De Minaur, who’d been nearly flawless in the opening exchanges, was suddenly being hurried into errors — 17 in the second set — as he lost seven games in a row across the second and third stanzas, looking increasingly bereft at the number of mistakes he was making.

Mensik, who’d been the last man to defeat Sinner before the world No.1’s capitulation here to Juan Manuel Cerundolo, went on another five-game hot streak, racing through the third set and breaking for a 3-0 lead in the fourth.

Feeling it all slipping away, de Minaur, uncharacteristically, hurled his racquet into the clay and smashed it, earning a code violation, after Mensik had put away a telling volley at 4-2.

He soon put de Minaur out of his misery, the Australian unable to dig out a fierce inside out forehand after two hours 25 minutes, leaving Daria Kasatkina as the only Australian left in the singles draws.

She will have her work seriously cut out to ensure there’s any Australian interest as she faces world No.1 Aryna Sabalenka on Court Suzanne Lenglen.