Denoting his 100th game responsible for the Reds on their first round of the 2017/18 battle, Jurgen Klopp drove his side to Hertfordshire searching for his 51st win.
Despite the fact that hampered by the disappointing news of Philippe Coutinho's transfer request, Liverpool manufactured on into the end of the week arranged to push for three focuses over the Hornets.
Alongside Coutinho (back), Nathaniel Clyne (back), Adam Lallana (thigh) and Daniel Sturridge (thigh) all missing the game because of damage(injury), yet Klopp could hand a opening debut to summer landing Mohamed Salah.
Having won 1-0 at Vicarage Road toward the finish of last season, the Reds will have been sure as they advanced down the M1, however it unquestionably demonstrated an extreme test.
Liverpool, arranging in their standard 4-3-3 arrangement, controlled the match from kickoff at Vicarage Road, yet it was Watford who made their stamp first.
After Stefano Okaka strung Roberto Pereyra through on the break, with Dejan Lovren hindering the Argentine's subsequent shot, the Hornets' No. 33 was available to head home the corner.
Watford kept on smothering the Reds in the primary half-hour, guaranteeing Klopp's midfielders had little time on the ball to sustain his new-look forward line.
However, with Sadio Mane lifting the bunch together in space, the Senegalese drove a general move, exchanging with Alberto Moreno and Emre Can, before twisting the ball past Heurelho Gomes to make it 1-1.
It wasn't well before the Hornets struck back, be that as it may, and it was Abdoulaye Doucoure who jabbed home from short proximity to put the home side ahead for the second time.
The Reds came back to toothlessness from that point, with Salah blasting over from the edge of the six-yard box and Mane missing with a header, as Anthony Taylor blew for half-time at 2-1.
Klopp picked against rolling out any improvements at half-time, keeping confidence with his beginning lineup, and was quickly remunerated for doing as such.
With the ball strung through for Salah into the case and Gomes hurrying out, the Egyptian dashed in and nipped it far from the Watford goalkeeper, brought down for a punishment the procedure.
Firmino, who resumed penalty obligations from James Milner, opening home, before turning supplier for Salah two minutes after the fact, with the winger scoring a debut goal to put Liverpool ahead.
Liverpool kept up control during the time half, and the pace of Salah specifically demonstrated reliably disturbing for Watford, frequently found past the home guard.
Georginio Wijnaldum had an awesome chance to put the good to beat all when found in the punishment range late on, however the Dutchman skewed.
That demonstrated crucial, as with Watford making a late rally at the inverse end, Miguel Britos tucked home to make it 3-3.