Claudio Ranieri was given an immediate warning as to the challenge he faces at Watford after the Italian watched his new team get torn apart by a Mohamed Salah-inspired Liverpool at Vicarage Road on Saturday.
Appointed Watford's new manager during the international break, Ranieri was handed a rough welcome on his return to the Premier League as Jurgen Klopp's rampant Reds ran out 5-0 winners.
Sadio Mane got the visitors under way in the ninth minute when the Senegalese forward slotted home his 100th Premier League goal with a first time finish on the edge of the area after racing onto the end of Salah's sumptuous curling cross.
From the moment Liverpool took the lead, and indeed since kick-off, it was all one-way traffic, and Roberto Firmino doubled their advantage seven minutes before the interval. The Brazilian striker grabbed his second shortly after the break, before Salah made it 4-0 with another stunning goal not dissimilar to the one he scored against Manchester City.
After jinxing through three Watford players, the Egyptian forward cut inside onto his left foot to send Craig Cathcart sliding in the wrong direction and curled the ball into the far right corner for his seventh league goal of the season.
"I was in the box trying to find someone or score myself," Salah, 29, said. "It is all about the team, that is the most important thing."
Watford did start to show greater ambition during the second half but were unable to trouble Liverpool goalkeeper Caoimhin Kelleher, and the visitors added a fifth in stoppage time as Firmino completed his hat-trick by slotting the ball home from a Neco Williams cross.
The result extends Liverpool's unbeaten start to the season and moves Klopp's side on to 18 points from their first eight games, while Watford remain on seven points.
"We talked in dressing room about starting the game well and that's what we did," Salah said. "All the goals were very important but Bobby (Firmino) did a great job scoring a hat-trick, so congratulations to him, and Sadio also scored a nice goal."
Former Chelsea manager Ranieri has plenty of Premier League experience, which includes guiding Leicester City to the most remarkable of league title triumphs in 2016, and the Italian will need to call on some of that magic to stabilise a Watford side considered among the favourites for relegation.
"I'm sure we can improve, we have to improve," Ranieri told BT Sport. "Now we have to work hard and slowly, slowly we can get better."
