Liverpool head for the Club World Cup in Qatar on Sunday with 16 wins from 17 Premier League matches and safe in the knowledge their commanding lead will not be troubled any time soon. Metaphorically and physically, they are disappearing over the horizon, 10 points clear after Leicester’s draw with Norwich.

This was far from a vintage display from the unbeaten leaders. They played within themselves and were flattered by the margin of victory delivered by two outstanding finishes from Mohamed Salah. Had Nigel Pearson inherited a player with even a hint of composure in front of goal then Watford would have given their new manager something more tangible from his first game than just an encouraging performance. The visitors created and squandered several excellent openings, with Ismaïla Sarr and Abdoulaye Doucouré the chief culprits.

Liverpool never got into their stride defensively or in attack. It was to be expected after the effort required to subdue Salzburg in a vital Champions League win in midweek yet they produced the flashes of ingenuity and quality to turn a difficult afternoon into another decisive step towards the title.

“It wasn’t an off day,” said Jürgen Klopp. “It was just a difficult game. December, January; you need to show resilience and we showed it and Watford did as well. We had chances and we scored goals. They had chances and they didn’t score. It is for sure one reason they are in the situation they are in.”

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Pearson could only concur. His new team have scored nine league goals all season and could, should, have had three here with Gerard Deulofeu denied by Alisson when clean through on goal in the second half. But in terms of organisation, discipline, spirit and promise, the new Watford manager has something to build on. “Hopefully that was a shift in what we have looked like this season,” he said. “We have got to play with that intensity in every game and if we do that there is a real possibility of turning the corner. But we have to make it happen ourselves.”

The first half had been a slog for Liverpool, to the obvious irritation of the home crowd, and highly promising for Pearson when one moment demonstrated the chasm between the top and bottom of the Premier League. It was not one Doucouré will recall fondly. Watford escaped several times behind James Milner, Andy Robertson’s replacement at left-back, and Troy Deeney was close to converting Sarr’s inviting cross in the opening minutes.

Sarr was involved again when he released Étienne Capoue down the right. From the byline, the midfielder rolled the ball back for the unmarked Doucouré to convert but he scuffed the shot horribly and Joe Gomez prevented Deulofeu pouncing on the loose ball. From the resulting, and wrongly awarded corner, Liverpool made Doucouré pay with a lightning counter.

Facebook Twitter Pinterest Nigel Pearson was unlucky not to take anything from his first match as Watford manager. Photograph: Carl Recine/Action Images via Reuters

Roberto Firmino released Sadio Mané with an overhead kick. The Senegal international sent Salah racing through but with plenty to do as Kiko Femenía came across to cover. With a flick of the instep Salah cut inside, leaving Femenía flailing, and curled a delightful finish around Ben Foster and inside the far post.

Until that point the leaders had been frustrated by Watford’s resilient defending, Foster slowing the game down by taking an age over goal kicks, and an unusual lack of cohesion among their forward line.

Liverpool escaped a second time when Alisson tipped Deulofeu’s low drive into the path of Sarr. The Senegal winger, no more than eight yards out and completely unmarked, sliced the shot skywards with his shin. Doucouré, somewhat inevitably, scooped the loose ball over.

Liverpool thought they had doubled their advantage when Mané steered a superb header beyond Foster from Xherdan Shaqiri’s delightful cross. Watford were about to restart in the centre circle when VAR made its belated intervention. Mané, VAR spotted following a lengthy review, was a fraction ahead of Craig Cathcart when Shaqiri delivered from the left. No goal.

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Deulofeu almost capitalised when released behind Trent Alexander-Arnold by Doucouré. Alisson rushed off his line to deny the former Everton winger with a crucial save and Liverpool continued to live dangerously.

Heavy first touches from Salah and Firmino allowed Foster to gather when the forwards were through on goal. At the other end Virgil Van Dijk almost put through his own net when he steered a wayward pass from substitute Andre Gray beyond Alisson but also just wide of goal. Deulofeu struck the outside of the near post with the resulting corner, Sarr volleyed another decent chance wide from the edge of the area and also appealed in vain for a penalty after a nudge by Van Dijk.

But Liverpool got the job done once more. In the final minute Mané broke and centred for Divock Origi. The substitute followed the day’s pattern for finishing in front of the Kop and scuffed his shot too, but it rolled on to Salah whose outrageous flick went through the legs of Christian Kabasele and in.

Another lengthy VAR review for offside followed before deciding in Liverpool’s favour. The leaders march on.