Jose Mourinho's team suffered their lowest point of the campaign by falling to a surprise second league defeat on Thursday
Tottenham were their conquerors, putting in a dominant display to earn a 5-3 triumph as Chelsea began 2015 in dreadful fashion.
The result left Mourinho's side, considered as certainties by many for the Premier League title just a few weeks ago, level on points with champions Manchester City at the top of the table.
Goalkeeper Petr Cech is among those likely to come in, while star men Diego Costa and Eden Hazard are strong candidates to be rewarded with a rest as a full-strength squad provides Mourinho with ample opportunities to rotate.
Watford's best run in the tournament came in 1983/84 when they reached the final.
They were beaten 2-0 by Everton in the Wembley showpiece, with Graeme Sharp and Andy Gray grabbing the decisive goals.
Among Watford’s current vintage, Hungary international midfielder Daniel Tozser is poised to make his FA Cup debut and insists his team-mates must take on their illustrious opponents without fear.
"Chelsea at the moment are in the top five teams in Europe," Tozser told Hornets Player on Watford's official website.
"But it will be a pleasure for the guys to play against a team like this. We have nothing to be afraid of, nothing to lose. This is a game we have to enjoy, to show and to see where we are at the moment.
"This is a game where we can show to our supporters that we have ambition. We want to play against these teams.
"The biggest mistake we can make is not to lose the game or make a mistake - it's a part of football, especially against a team like this. If we really want to show what we can do, we must not be afraid."
The former emerged triumphant on both occasions, claiming a 3-1 away victory in a fifth-round contest in 2009 before cruising to a 5-0 home success in the third round the following year.
