Novak Djokovic suffered his heaviest defeat in a three-set match on Friday when he was knocked out of the Vienna ATP tournament by lucky loser Lorenzo Sonego, stalling his bid to wrap up the year-end world number one ranking for a sixth time. Italian Sonego, ranked 42 and who had initially lost in qualifying last weekend, is the first lucky loser ever to beat Djokovic. His 6-2, 6-1 quarter-final stunner was 33-year-old Djokovic's heaviest ever defeat. The only other time he had won just three games was at the 2005 Australian Open at the hands of Marat Safin in a best-of-five-set encounter.
Friday's defeat means Djokovic will have to wait a little longer before he completes the formality of equalling Pete Sampras's all-time record of ending the season top of the rankings for a sixth time.
"For sure it's the best victory of my life. Novak is the best in the world. Today I played so, so good," Sonego said.
"It's unbelievable. It's amazing. I played the best match in my life. I'm so happy for this."
Sonego fired 26 winners past the Serb who lost for only the third time in 2020.
Djokovic, a 17-time major champion, managed just seven winners against 25 unforced errors.
Second seed and defending champion Dominic Thiem also lost on Friday, going down 7-6 (7/5), 6-2 to Russian world number eight Andrey Rublev.
Rublev hit 30 winners past the US Open champion and goes on to face South Africa's Kevin Anderson for a place in the final.
"I came here with the mood that I have nothing to lose," said Rublev who is chasing a fifth title of the year.
"I had already a really great season. I came here with zero expectations, just wanting to do my best. To try to fight every match. At the end, I am here in the semi-finals."
Anderson made the semi-finals by accounting for Russian fourth seed Daniil Medvedev 6-4, 7-6 (7/5).
It was Anderson's first top 10 win in two years.