Britain's Kyle Edmund pushed world number one Novak Djokovic before fading to a straight-set defeat in the Paris Masters third round.
Edmund, expected to be Great Britain's last pick for next month's Davis Cup finals in Madrid, lost 7-6 (9-7) 6-1 against the 32-year-old Serb.
Edmund, 24, caused Djokovic problems before the top seed finally clinched the opener with his seventh set point.
But Edmund could not maintain his level as Djokovic ran away with victory.
The 16-time Grand Slam champion, who has been suffering with illness and sounded hoarse in his post-match interview, started to hit the ball cleaner in a second set where he made just four unforced errors.
Despite defeat, Edmund can take plenty of positives from an encouraging week which should seal his place in the British team going to Madrid for the newly revamped Davis Cup finals.
The Yorkshireman came into the final ATP Masters tournament of the year without a win since the start of August, but has enjoyed a timely return to form in the French capital.
Edmund, who had lost eight matches in a row, has stolen a march on Cameron Norrie to be named in Leon Smith's squad following victories over Lithuanian qualifier Ricardas Berankis and Argentine 14th seed Diego Schwartzman this week.
Edmund looked confident and assured for most of the first set, matching Djokovic until a couple of mistakes as he served to stay in the opener at 6-5 gave the Serb two set points.
However, he rallied to force a tie-break and saved four more set points before finally buckling when Djokovic hit a precise forehand down the line.
The second set was a different story, however, as Edmund ran out of steam and won just nine points in a one-sided set.
Four-time Paris champion Djokovic will now play Greek seventh seed Stefanos Tsitsipas, who beat Australian Alex de Minaur 6-3 6-4, in the quarter-finals.
Spanish 19-time Grand Slam singles winner Rafael Nadal boosted his hopes of ending the year as world number one with a 6-4 6-4 win over Swiss Stan Wawrinka. He is guaranteed to knock Djokovic off top spot next week, but will stay at the summit going into the next season if he wins his first Paris title.
Elsewhere, Bulgaria's Grigor Dimitrov produced a powerful performance to beat Austrian fifth seed Dominic Thiem 6-3 6-2 and will face Chile's Cristian Garin next.