World number one Novak Djokovic had enough on his plate already on Wednesday without marauding Russian Daniil Medvedev pummelling him to a shock 6-3 6-3 defeat at the ATP Finals.
Shortly after news broke that Djokovic had been nominated for a return to the ATP player council he had quit in August , he took to court at the O2 Arena hoping to seal his passage into the semi-finals of the prestigious year-ender.
Instead his progress out of the Tokyo Group looks tricky, even if not quite as complicated as the politics rumbling on in men's tennis since he announced in August he was forming a breakaway Professional Tennis Players' Association (PTPA).
Medvedev's sensational performance means he is guaranteed top spot in the group and Djokovic, bidding to match Roger Federer by winning the title for a record-equalling sixth time, must beat 2018 champion Alexander Zverev in his last round-robin match on Friday.
There was little sign of what was to come in a mesmerising opening to the match as Djokovic edged into a 3-2 lead.
But the 24-year-old Medvedev, his flat groundstrokes scorching through the court, found a gear that even indoor master Djokovic could not locate.
Pummelling his high-velocity groundstrokes deep into the corners, Medvedev had Djokovic burning rubber and went on a near-perfect seven-game winning streak to leave his bemused opponent puffing out his cheeks.
By the time 17-time Grand Slam champion Djokovic managed to stop the rot he was a set and 3-1 in arrears.
Medvedev was relentless and continued to boss the baseline rallies as he extended his lead to 5-2.
Djokovic held serve to at least ask the question of Medvedev's nerve but the Russian was ice cool as he closed out victory to make it two wins from two in the group, while handing Djokovic only his fourth defeat of 2020.
Medvedev, who made only 12 unforced errors, lost all three of his group matches on his ATP Finals debut in London last year, but now looks like a genuine title contender.
"I just had a pretty bad seven games in a row," Djokovic, who himself lost all three matches on his debut at the ATP's jewel in the crown in 2007 before taking the title in 2008, said.
"In no time it was 6-3, 3-0. He was just better, no question about it. I struggled to find the right rhythm for 15 minutes or so. I could have and should have done better, but credit to him for playing on a high level."
Medvedev did what Djokovic has done to countless opponents. Having absorbed the Serb's best early on, he broke serve in an extended game at 3-3 and then ran the legs off his increasingly dispirited and ragged opponent.
"I'm sure he didn't play his best but it happens to everybody," the world number four, who warmed up for London by winning the Paris Masters, said.
"I always say the Big Three are champions because it happens to them less than everyone else. I'm feeling confident. I knew I had to take my chances and it was a great match for me."
While he will go into his final group match against Diego Schwartzman with no stress, Djokovic faces a straight shoot-out with Zverev to avoid an early exit.
Earlier Zverev bounced back from his defeat by Medvedev to beat Argentine debutant Schwartzman 6-3 4-6 6-3.
Leading by a set and 3-1 Zverev looked to be cruising despite some serving issues but allowed Schwartzman back before finally making his extra firepower count.