World number one Novak Djokovic was unceremoniously dumped out of the Erste Bank Open in Vienna by lucky loser Lorenzo Sonego, 6-2 6-1.
It is the biggest win of the Italian's career, taking him through to the Vienna semi-finals. And less than a week ago he was not in the main draw at all, falling in the final round of qualifying to Aljaz Bedene.
Since getting his place in the tournament as a lucky loser, however, he has not dropped a set.
"For sure it's the best victory of my life," Sonego said in an on-court interview. "I played so, so good today. I like this tournament, I like the conditions here. It's unbelievable."
Djokovic had six chances to break Sonego in two second-set games but could not do so, and continued to serve up multiple unforced errors, with his forehand looking particularly weak.
The Serbian seems to have already sealed his place as the men's year-end number one, but winning the title this week would have guaranteed it.
"I've done what I needed to do and why I came here. I move on completely fine with today's result and looking to the next chapter," Djokovic said. "I'm healthy and looking forward to a strong finish in London [for the ATP Finals]."
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Earlier, Russia's Andrey Rublev ousted defending champion Dominic Thiem 7-6(5), 6-2, firing 30 winners and saving both break points he faced.
With neither player dropping serve in the opening set, it was Rublev who managed to swing the momentum his way in the tiebreak with what he described as "two unreal rallies" at 4-3 before early breaks in the second allowed him to seal the tie.
Rublev is seeking a Tour-leading fifth title of the year having won in Doha, Adelaide, Hamburg and, most recently, St Petersburg earlier this month.
"I came here with the mood that I have nothing to lose," Rublev said. "I already (had) a really great season.
"I came here with zero expectations, just to do my best. To try to fight every match. At the end, I am here in the semi-finals."
Additional reporting courtesy of Reuters