Novak Djokovic was knocked out in the quarter-finals of the Vienna Open after winning just three games in a 6-2 6-1 loss to Lorenzo Sonego.

Djokovic wins just three games in shock defeat to Sonego at Vienna Open

World number one Novak Djokovic is out of the Vienna Open after a shock 6-2 6-1 quarter-final defeat to unfancied Lorenzo Sonego.

Ranked 42 in the world, Sonego had failed to win a single set in his three previous meetings with players inside the top 10.

But the Italian produced a scintillating performance against the top seed as he became the first lucky loser to beat Djokovic.

"It's unbelievable. It's amazing," Sonego said in an interview on court after wrapping up the win in 68 minutes.

"For sure, it's the best victory of my life. Novak is the best in the world. I played so, so good.

"I like it here, I like the conditions. It's so fast for my serve. I was so focused on my tennis - I served well and returned good."

Djokovic's surprise exit at the Wiener Stadthalle meant the Serbian missed the opportunity to guarantee top spot in the year-end ATP Rankings this week.

The 33-year-old is still poised, however, to tie Pete Sampras' record of six year-end number one finishes unless Rafael Nadal takes up an unlikely wildcard for next month's Sofia Open, with reports indicating the Spaniard has already rejected such an opportunity.

Djokovic began sluggishly in what was a first career meeting between the two men, suffering a break in the first game with a loose forehand.

Sonego then held his own serve before he broke again in the third game, and although Djokovic briefly rallied at 5-2, the Italian confidently held serve to clinch the first set.

The 25-year-old, who turned professional in 2013 and won his solitary ATP Tour title – the Antalya Open – last year, carried the momentum into the rest of the match.

Djokovic earned three break points at 2-1 down in the second set, but the Serbian failed to take his chance to get back on serve and from there was no way back as Sonego clinically closed out the match.

"He just blew me off the court, that is all," said Djokovic. "He was better in every segment of the game.

"It was a pretty bad match from my side, but amazing from his side. He definitely deserved this result."

Defending champion and second seed Dominic Thiem was also knocked out of the tournament.

Russian Andrey Rublev beat the Austrian 7-6 (7-5) 6-2 to secure his place in the last four as he increased his ATP 500 winning streak to 13 matches.

Rublev will face South African Kevin Anderson, who reached his first ATP semi-final since the Maharashtra Open in January 2019.

Anderson overcame world number six Daniil Medvedev of Russia 6-4 7-6 (7-5) to book his spot.