Liverpool's 44-match unbeaten run in the Premier League came to an abrupt end with its first loss of the season in a 3-0 reverse at Watford on Saturday, Ismaila Sarr and Troy Deeney combining to down the Reds.
Jurgen Klopp's men went into the clash at Vicarage Road on the back of 18 successive league wins, one short of a new record, but the bright Hornets were thoroughly deserving of the victory to boost their survival hopes.
Watford's promising start looked as though it might go to waste when Gerard Deulofeu – its chief threat – was forced off with a potentially significant knee problem before half-time.
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But the home side maintained its level after the interval and the lively Sarr was hugely effective with two goals, and Deeney finished them off 17 minutes from the end as Liverpool's hopes of an 'invincible' season were vanquished.
Liverpool offered little in a muted first-half display, with Watford looking much livelier in attack through Deulofeu.
He troubled Trent Alexander-Arnold twice early on as he put a couple of shots just off target, cutting inside and curling an effort just over the top-right corner inside the box for the second.
But the Spaniard's match ended early in the 37th minute when he had to be carried off on a stretcher, having seemingly suffered a serious knee injury during a tussle with Virgil van Dijk.
Watford was unlucky to not lead just before half-time – Alisson making a mess of a routine collection, but Deeney failed to capitalise.
Liverpool failed to improve after the interval and Watford eventually got a deserved opener, as Abdoulaye Doucoure latched on to a throw-in and lashed the ball into the danger zone for Sarr to prod home.
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The winger got a second in even more impressive circumstances soon after, chasing Deeney's brilliant throughball behind Van Dijk and cheekily lifting his finish over the approaching Alisson.
Sarr was crucial again for Deeney's clincher, chasing down Alexander-Arnold's woeful back-pass and teeing up his strike partner who calmly turned in with Alisson in no-man's land.
What does it mean? Watford gives the rest hope and boosts survival chances
Liverpool's lead at the Premier League summit remains a hugely impressive 22 points even with this defeat, but Watford exposed its weakness – playing behind the full-backs – impressively, potentially giving a little inspiration to the rest of the pack.
Manchester City certainly will not be predicting a collapse from the Reds that allows them a way back in, but if anything can renew hope, it is this, with Watford - now out of the bottom three on goal difference - surely full of confidence in its relegation tussle
Watford's young winger has enjoyed some impressive performances in big games this season, but this was on another level. Two goals and an assist, you cannot ask for much more than that.
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Alexander-Arnold all at sea
The Liverpool and England right-back has rightly received much praise for his creative abilities this season, but questions have been raised about his defensive attributes and concentration at the back, and they will likely appear again after this horror show.
Liverpool turns its attentions to the FA Cup next, as it goes to Chelsea in the fifth round on Tuesday, before hosting Bournemouth in the Premier League four days later. Watford's fight to avoid relegation resumes at Crystal Palace the same day.