For the first time since January 3, 2019, Liverpool have tasted defeat in a Premier League match.
Ismaila Sarr's second-half double and Troy Deeney's strike earned relegation-threatened Watford a surprise 3-0 victory at Vicarage Road on Saturday.
Though it is unlikely to prevent the Reds from lifting the title - with Jurgen Klopp's side still 22 points clear of Manchester City - it did stop them from surpassing Arsenal's record sequence in Premier League history.
Here we recall how the longest unbeaten runs in Premier League history ended.
ARSENAL (2003-04) - 49-MATCH STREAK ENDED BY 2-0 LOSS TO MANCHESTER UNITED
Behind fans of the Hornets, Arsene Wenger's 'Invincibles' were probably the happiest about Liverpool's loss on Saturday.
Their record run, which spanned between May 2003 and October 2004, included an entire campaign unbeaten - just the second in English top-flight history after Preston North End in 1888-89.
It was their great rivals of the time that prevented them from reaching 50 unbeaten, though, Ruud van Nistelrooy and Wayne Rooney scoring in a 2-0 victory at Old Trafford in a contest best remembered for 'Pizzagate', with Manchester United boss Alex Ferguson hit by a slice in the tunnel after the game.
LIVERPOOL (2019-2020) - 44-MATCH STREAK ENDED BY 3-0 LOSS TO WATFORD.
The Reds arrived at Vicarage Road having dropped just two points all season.
Yet in their 28th Premier League game of 2019-20, they were left with an unfamiliar feeling as Nigel Pearson's Hornets succeeded where no one else had in the campaign.
It was all the more remarkable given the Reds had won their previous 18 successive league games and Watford were winless in their past eight meetings against the Reds.
CHELSEA (2004-05) - 40-MATCH STREAK ENDED BY 1-0 LOSS TO MANCHESTER UNITED
The Blues were dominant in Jose Mourinho's maiden season in his first spell at Stamford Bridge, winning the title and finishing 12 points above Arsenal with 95 in total.
A 1-0 away loss to Manchester City in October 2004 was their only top-flight loss of that campaign and it was 13 months before they tasted defeat again, in the same city.
Darren Fletcher scored the only goal as United beat Mourinho's side 1-0 at Old Trafford, though it was Chelsea who would end the season with the last laugh as champions again.
ARSENAL (2001-02) - 30-MATCH UNBEATEN STREAK ENDED BY 2-1 LOSS TO EVERTON
Wenger's great teams had a habit of avoiding defeats and the bulk of this sequence occurred during their double-winning season of 2001-02.
Everton were beaten twice in a 13-game winning run to end that term but they got their revenge the following October through a then largely unknown striker.
It appeared as if the Gunners were on course to make it 31 unbeaten at Goodison Park but a 16-year-old Rooney had other ideas, curling a brilliant 30-yard strike in off the crossbar in the final minute for his first Premier League goal.
MANCHESTER CITY (2017-18) - 30-MATCH UNBEATEN STREAK ENDED BY 4-3 LOSS TO LIVERPOOL
Pep Guardiola's side from two seasons ago was perhaps the best the Premier League has ever seen as they won the title with 100 points and having scored 106 goals.
Yet they did suffer two league losses in that campaign, the first occurring as Klopp's men won a thriller at Anfield by scoring three times in an eight-minute spell to go 4-1 up.
City netted twice in the final six minutes but fell short at a ground where they had not won since 2003.