Liverpool’s Thiago Alcantara, left, and Diogo Jota. Picture: Michael Regan/Getty Images
However, the Reds are sweating on several key players for the clash against the Hornets.
We take a look at who is doubtful for the game and how likely they are to be involved.
The striker's injury problems he's suffered while on international duty have been well documented.
Jota was sent back to Anfield early due to suffering a muscle injury while with Portugal.
He sat out their 3-0 friendly win over Qatar before flying home before the 5-0 thrashing of Luxemburg.
However, the fact that Jota continued to train with Portugal for a period bodes well in Liverpool's favour.
Had his issue been more serious, the ex-Wolves forward would have come back to Merseyside a lot sooner.
Roberto Firmino was not called up to Brazil duty having recently recovered from a hamstring issue.
Firmino came off the bench in the past two games and has continued to train with Jurgen Klopp's troops at Kirkby over the past few days.
He's a sound option to start.
Verdict: on the bench
The right-back missed Liverpool's 5-1 thrashing of Porto and 2-2 draw against Manchester City because of an adductor problem.
James Milner deputised superbly in the first game but was lucky not to be sent off in the City clash for a second yellow card when hacking down Bernado Silva.
Before the Porto trip, Klopp admitted a couple of his players had minor issues.
Alexander-Arnold was one of them and he was also left out of the England squad.
However, he's back in full training and it'd be a surprise if he doesn't feature from the outset.
The midfielder's enjoying a good run in the Liverpool team, starting the past four games in all competitions.
Jones linked up with the England under-21 squad during the international break but missed their first game - a 2-2 draw with Slovenia - with a knock.
However, the academy product came off the bench in the young Lions' following fixture in Andorra.
During his 33-minute cameo, Jones provided the magic to assist Emile Smith-Rowe's match-winner.
That suggests that he should be OK when he links up with Liverpool and looks in line for another outing.
The midfielder has missed the past four games after sustaining a calf injury in the 3-0 defeat of Crystal Palace last month.
Thiago will be desperate to get back to full fitness as he bids to show his worth after a frustrating maiden season last campaign.
However, the former Bayern Munich man was not snapped in training ground photographs on Tuesday.
A day later, Thiago posted a picture on his Instagram story of himself duringn rehabilitation in the gym.
That suggests Thiago's recovery is going to plan but the Vicarage Road encounter may come too soon.
There are doubts if the keeper will make it back to England in time for kick-off.
Brazil play Uruguay at 01.30 BST on Friday, giving Alisson less than 36 hours to return to these shores.
Perhaps there might have been a temptation to play the ex-Roma stopper had he been serving as No.2.
However, he's already featured in games against Venezuela and Colombia and that suggests he may feature for a third time.
If Alisson is on the bench, there's a slim chance he might be involved at Watford but it looks like a close call.
The holding-midfielder is in the exact same position at Alisson.
Fabinho has too played the entirety of Brazil's games.
His chances are even shorter than his compatriot's of featuring against the Hornets.