Liverpool have lost their first Premier League game for 14 months - getting thumped 3-0 by relegation-threatened Watford.
Watford had won just five of their 27 games this season before the runaway leaders came to Vicarage Road on Saturday evening.
Liverpool, who last lost on 3 January 2019 to Manchester City, had been hoping to set a new Premier League record of 19 straight wins.
They also won't be emulating Arsenal's "invincibles" of 2003-04 in going a whole season unbeaten.
Arsenal sent Liverpool their commiserations with a tweet after the match.
The Reds had not lost any of their previous 44 games and had only dropped points once this season before the tea-time kick-off.
The defeat is unlikely to affect the destination of this year's league title, with the Reds needing to win just four of their remaining 10 games to clinch a first title in 30 years.
They remain a huge 22 points ahead of second-placed Manchester City, who have a game in hand.
That did not stop Sky Sports pundit and former Manchester United defender Gary Neville - whose own side are 38 points behind Liverpool - celebrating the shock result, posting a video of himself opening a bottle of champagne on Twitter.
The win moves Watford out of the relegation zone.
Ismaila Sarr scored twice while captain Troy Deeney added a third in a stunning second-half display.
Liverpool manager Jurgen Klopp responded: "You have to accept it, it's not so easy, but it's the proof we were not good enough tonight. It's always very difficult.
"We have to accept if after. In the game you have to fight. We were 3-0 down but we still tried, there were no silly situations where somebody got frustrated and tried to kick someone.
"If you win good, if you lose, try to do it in the right manner and do it like a man."