Daniil Medvedev steamrollered an out-of-sorts Novak Djokovic to book his place in the semi-finals of the Nitto ATP Finals in London.
The Russian, who failed to win a match on his debut last year, reeled off seven games in a row at one point and never looked like faltering in a 6-3 6-3 victory.
That guaranteed Medvedev will top the Tokyo 1970 group while Djokovic, who has his sights set on a record-equalling sixth title, faces a straight fight against Alexander Zverev for the second qualifying spot.
It was the second day in a row that the O2 witnessed the defeat of one of tennis’ leading duo but, unlike Dominic Thiem’s pulsating battle with Rafael Nadal, this was not particularly close.
Djokovic’s second serve took a pounding at the hands of Medvedev, who arrived in London with confidence high after winning the Paris Masters earlier this month.
Both men had been relatively untroubled in their opening contests, Djokovic beating Diego Schwartzman and Medvedev seeing off Zverev, and straight away there were lung-busting rallies as each tried to grab the upper hand from the baseline.
Medvedev is an exceptional mover for his height of 6ft 6in and time and again his long levers allowed him to retrieve one more ball than Djokovic was expecting.
The world number one saved two break points in the third game but more chances arrived in the seventh game and this time Medvedev came out on top of another corner-to-corner rally to seize the advantage.
Both men sucked in air as they sat down at the change of ends but it was Medvedev who was suffocating Djokovic with the excellence of his play and he won his fourth successive game to clinch the set.
The drop shot was again proving more of a liability than a help to Djokovic while his serve was well below par, the top seed sending down his fourth double fault of the match on set point.
And there was no shift in momentum at the start of the second set, Djokovic looking bereft of ideas as Medvedev broke serve for a third successive time.
He finally stopped the run of games against him by holding for 3-1 but a comeback never looked on the cards and Medvedev comfortably wrapped up victory.
Earlier, Zverev enjoyed with a three-set win over Diego Schwartzman.
Zverev, the 2018 champion, was dejected after losing to Medvedev in his opening match, and there were plenty of holes to pick in this performance, too, but the German emerged a 6-3 4-6 6-3 winner.
Argentinian debutant Schwartzman was staring at a second convincing loss after Monday’s defeat by Djokovic when he trailed 3-1 in the second set and faced points for a double break.
But he fought back to win five out of the next six games and take the match to a decider. It was Zverev who stepped up when it mattered, though, winning five of the last six games to end the match.
The German will need to beat Djokovic on Friday to have a chance of reaching the last four, and will surely need to play at a consistently-higher level.
He said in his on-court interview: “It was much better than on Monday. Diego’s a very difficult player.
“I’m happy to get the win, I’m happy to give myself a chance. Friday is going to be the most difficult match you can have here against Novak. I’m looking forward to it.”
