Sam Querrey enjoyed the biggest victory of his career to date, as he recovered from the loss of the opening eight games to beat Novak Djokovic in the second round of the Paris Masters.
The world No 23 American, who lost his opening four service games, appeared to be heading for the exit door before conjuring up a remarkable fightback to beat the No 2 seeded Serb 0-6 7-6 (7-5) 6-4 in two hours and seven minutes.
After winning just 11 points during the first eight games, the 25-year-old from Las Vegas suddenly discovered his range - particularly with his serve - to secure his first ever victory against a player ranked in the world's top three.
He collected his first break in game four of the second set, before edging the tie-break on his first set point.
The only break of the final set came in game five, although Querrey was pushed to the limit when serving at 4-3.
From 15-40 down, he went on to save four break points before sealing a famous triumph on his second match point when the five-time Grand Slam winner could only push another fierce Querrey serve beyond his opponent's baseline.
World No 1
Despite the defeat, Djokovic will end the season as world no 1, and will replace Roger Federer at the top of the rankings next week.
Querrey fired 18 aces to five from his opponent whose defeat leaves Andy Murray as the highest seed left in the tournament.
Djokovic had complained earlier this week about the lack of a rest week prior to the season-ending World Tour Finals which begin in London on Monday.
The Serb had said he was trying to conserve his strength for the final event and he will now have almost a week to prepare for the season's finale.
"It is a big challenge," he said. "Obviously I'm sure all the participants in London will agree that this is definitely not something that goes in the favour of us preparing for the most important event in the end of the year."
Djokovic, who had not played since beating Andy Murray in the Shanghai Masters final last month, had won his previous 10 matches.