Rafael Nadal is out of the Paris Masters after a second-round defeat to American Thomas Paul in just the Spaniard’s second match since the US Open and first since becoming a father.
World number 31 Paul came from a set down to beat Nadal 3-6 7-6 (7-4) 6-1.
Defeat for Nadal, who has battled an abdominal injury since the summer, saw his hopes of ending the year as world number one suffer a huge blow.
Britons Dan Evans and Jack Draper were also eliminated in the second round.
Nadal, 36, has only played once – a Laver Cup doubles match alongside Roger Federer – since losing in the fourth round of the US Open in early September.
He faded towards the end of the second set against Paul, 25, who secured one of the wins of his career.
The Paris Masters is the final regular ATP Tour event of the season, before the ATP finals get under way in Turin on 13 November.
Both titles are missing from 22-time Grand Slam champion Nadal’s illustrious trophy cabinet.
Bad day for the Brits
Elsewhere, Britain’s Dan Evans dropped out of the tournament following a second-round defeat by world number five Stefanos Tsitsipas, while compatriot Jack Draper lost to American Frances Tiafoe.
British number two Evans, 32, was beaten 6-3 6-4 by Greece’s Tsitsipas.
Draper, 20, fell to a 6-3 7-5 loss against US Open semi-finalist Tiafoe.
Cameron Norrie, the last Briton remaining in the draw, plays France’s Corentin Moutet in his second-round match in Paris later on Wednesday.
Tsitsipas, 24, recorded breaks of serve early in both sets against Evans, ranked 27th, and awaits the winner of Norrie’s meeting with Moutet in the third round.
World number 21 Tiafoe made the breakthrough in the eighth game against left-hander Draper before saving two break points as he served out the opening set.
British number three Draper, 45th in the rankings, was a game away from levelling the contest at 5-4 as the second set continued on serve, but Tiafoe closed out the match by winning three successive games.
Draper will contest the upcoming NextGen ATP finals for the season’s best players aged under 21, which takes place in Milan, from 8 November.
Former world number one Andy Murray lost his opening match against Frenchman Gilles Simon on Monday.
Daniil Medvedev also suffered a surprise defeat by Alex de Minaur in his second-round match.
Russia’s Medvedev, who won the US Open last year, lost 6-4 2-6 7-5 to the Australian.