Watford also suffered defeat last weekend as they went down 3-0 at Arsenal, and back-to-back away trips to top-six opposition will be a test of how far they have come under new manager Javi Gracia.
With United, Tottenham and Chelsea all in FA Cup action this weekend, the visit of Watford gives Liverpool the perfect opportunity to consolidate their top-four spot and close the gap to the Red Devils in second.
Jurgen Klopp's side have dropped to fourth in the table courtesy of their loss at Old Trafford, but victory over the Hornets will lift them back above Spurs and to within a point of United as distant runners-up to Manchester City.
The defeat to their fierce rivals was just their second in the Premier League since October, but they remain unbeaten at home in the top flight this season, the only team other than the Citizens to still hold that record.
News of Harry Kane's injury layoff will have been greeted fondly by Mohamed Salah as the Egyptian winger looks to become the first non-striker to win the Golden Boot since Cristiano Ronaldo in the 2007-08 season.
Salah has exceeded all expectations to bag 24 league goals this term, which sits him level with Kane at the top of the scoring charts, and also puts Ronaldo and Luis Suarez's co-record of 31 in a 38-game season within his reach.
The blank in Manchester ended Salah's six-game league scoring streak, but against Watford he can continue his run of scoring in every top-flight game at Anfield in 2018, which has yielded a total of seven goals in five matches.
Liverpool's front three have helped them score at least two goals in each of their last six home league matches, and the big-money signing of Virgil van Dijk has solved some of their problems at the other end, although not all of them.
Klopp's side have impressively overcome the departure of Philippe Coutinho and are well fancied to qualify for the Champions League again, but they cannot afford any slip-ups now that Chelsea and Spurs are out of Europe.
Recent Premier League form: WDWWWL
Recent form (all competitions): WWWWDL
The 3-0 reverse at the Emirates Stadium might seem like a comprehensive defeat, but the Hornets more than held their own for an hour against Arsenal and it may have been a different result had Troy Deeney not missed a second-half penalty.
Watford's captain ended up eating his words, having accused the Gunners of lacking "cojones" following their late capitulation at Vicarage Road in October, as his spot kick was saved by Petr Cech minutes after Arsenal had taken a two-goal lead.
The defeat was only Watford's second in six matches under new manager Gracia, but the Spaniard is yet to oversee an away win since taking over from Marco Silva, losing twice and drawing once with all three of his wins so far coming at home.
Watford's four victories on the road this season is only bettered by Burnley and the top five, but three of those came in their opening three matches and they have lost seven out of eight in the league since winning at Newcastle United in November, failing to score in their last four.
The trip to Merseyside will be another test of the Hornets' new defensive resolve, which had seen them keep three clean sheets in five matches prior to their encounter with Arsenal, having previously gone 12 games in the league without a shutout.
Stopping the late-Silva slide has seen Watford keep hold of the top-half position that they have occupied for much of the season, although defeat at Anfield coupled with a Bournemouth win over West Bromwich Albion could see them drop to 11th.
Recent Premier League form: DWLWWL
Klopp could restore Jordan Henderson to his starting lineup after Liverpool's club captain remained on the bench against United. There is also the choice of Georginio Wijnaldum or Alex Oxlade-Chamberlain in the midfield three.
Trent Alexander-Arnold and Dejan Lovren were targeted as weak links by Jose Mourinho, and Joe Gomez and Joel Matip could be the beneficiaries of their struggles at Old Trafford if Klopp decides that his defence needs a reshuffle.
Loris Karius has established himself as Liverpool's number-one goalkeeper, and that seems to be the case with Oscar Karnezis at Watford too with the Greek international continuing to keep Heurelho Gomes out of the lineup.
Injuries to Tom Cleverley and Gerard Deulofeu limit Gracia's midfield options so Kiko Femenia may be deployed on the right wing again, unless Andre Gray, who last started in the league in January, is recalled in an attack-minded move.
Liverpool possible starting lineup:
Karius; Gomez, Matip, Van Dijk, Robertson; Oxlade-Chamberlain, Henderson, Can; Mane, Salah, Firmino
Watford possible starting lineup:
Karnezis; Janmaat, Mariappa, Prodl, Holebas; Capoue, Doucoure; Richarlison, Pereyra, Femenia, Deeney
Head To Head
These two sides served up a six-goal thriller on the opening day of the season as Liverpool twice came from behind to lead, only for a stoppage-time equaliser from defender Miguel Britos to snatch the Hornets a point.
Goals have been aplenty in recent meetings, with 24 across seven games including a 6-1 Liverpool victory in this fixture last season. There has never been a goalless draw between these two teams in the league, although there have been two in the FA Cup.
Watford's only Premier League triumph over the Reds came in their maiden season in 1999-2000, when they won 1-0 at Anfield courtesy of a strike from Tommy Mooney, the highlight of a campaign which saw them finish bottom of the table.
We say: Liverpool 3-0 Watford
Gracia has found his feet at Vicarage Road but Watford have struggled on the road long before his arrival, and there may not be a more daunting away trip in the Premier League than Anfield when Liverpool's exciting attacking play gets the crowd up.
The Hornets do not have much to play for over the remainder of the season and have tailed off at around this stage in previous campaigns. Anything but 100% focus and commitment will not be enough to withstand the force of Salah and company.