Fabinho celebrates scoring their second goal with Jordan Henderson and Roberto Firmino on Saturday. Reuters
Jurgen Klopp's men edge two points ahead of Manchester City, who travel to Burnley later on Saturday, having trailed the English champions by 14 points just over two months ago.
The visit of the Hornets kicked off a huge month for the Reds as they remain in the hunt for a historic quadruple of trophies.
A potential title decider away to City next weekend falls in between both legs of a Champions League quarter-final against Benfica before another meeting with City in the FA Cup semi-finals.
Klopp could afford the luxury of leaving Luis Diaz and Sadio Mane on the bench after their exertions on international duty, alongside Trent Alexander-Arnold on his return from injury.
However, the hosts did not have the easy afternoon Klopp would have hoped for with tougher tests to come.
Mohamed Salah in action with Watford's Kiko Femenia. Reuters
Watford are in desperate need of points for their own battle to beat relegation. Ismaila Sarr started alongside Mane as Senegal beat Mohamed Salah's Egypt on penalties for the second time in less than two months to add World Cup qualification to winning the Africa Cup of Nations on Tuesday.
Sarr was included from the start by Roy Hodgson and was a major threat as he nearly caught Alisson Becker off his line early on.
Liverpool needed the Brazilian goalkeeper to be at this best for a few seconds that decided the game midway through the first half.
Alisson stood his ground to parry Juraj Kucka's powerful low effort when the Slovakian waas played through on goal.
The home side swiftly broke up the other end and Alexander-Arnold's deputy, Joe Gomez, swung in a cross and Jota nipped in ahead of Ben Foster to head in his 20th goal of the season.
But there was a nervousness around Anfield as Watford refused to wilt and even had a glorious chance to equaliser in the second half.
Sarr again created the danger with a burst down the left and his cut back was slotted wide by Joao Pedro.
Liverpool had to wait until a minute from time to get the two-goal cushion they desired when Kucka wrestled Jota to the ground from a corner.
Salah had already been subbed by Mane at that stage so Fabinho took responsibility from the spot and smashed into the top corner to secure Liverpool's 10th consecutive Premier League win.
Liverpool extended their perfect start to the Premier League season as Mohamed Salah inspired an impressive 3-1 win over Arsenal,
The Egypt international, who signed a new five-year deal in 2018, was the top scorer at the club this season with 17 Premier League goals as they secured a 19th top-flight title with seven games to spare.
The English top flight faces an eye-watering estimated loss of around £1 billion ($1.25 billion) if no more football is played due to the global pandemic.
Both teams now qualified for the second edition of the ANOC World Beach Games, which will take place in Bali, Indonesia, on Aug.5-12, 2023.
The Sharjah Sports Club team won the Kata discipline for the fourth time running and Kumite for the third time to top the general ranking for men after garnering 598 points in the 2022-2023 season.
Messi's opener was cancelled out by a Kevin Gameiro equaliser, but the result gave PSG an unassailable four-point lead over second-placed Lens with one match of the season remaining.