The game will kick-off at 7pm as the young Hornets look to book their place in the quarter-finals of the competition.
Matt Bevans’ Under-18s have already progressed through the third and fourth rounds to earn the game with the North London side.
In the third round they beat Oxford 2-1 at Kings Langley FC thanks to an instinctive strike from Kash Odiase.
Then, in the fourth round, Amin Nabizada netted twice as the Hornets were impressive 4-1 winners against Crewe at the Orbital Fasteners Stadium.
Spurs beat Middlesbrough 3-2 in the third round, before seeing off a fightback from Grimsby in the fourth round.
Spurs were 3-1 up at Blundell Park going into the last minute but the Mariners scored twice to take the game to extra time before Tottenham went on to win 5-3.
The Hornets have a proud FA Youth Cup history, winning the trophy in both 1982 and 1989.
Tickets for the tie are currently on sale, and admission is free if you are a season ticket holder.
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Fans can get their tickets from tickets.watfordfc.com, over the phone on 01923 223023 and in-person at the Supporter Services & Ticketing Office at Vicarage Road.
Watford season ticket holders can attend for free, but their seats will need to be pre-booked.
Adult tickets are priced at £5 and those aged 18 & under can secure their seat for £1, with all seating reserved in the Sir Elton John Stand.
One team, West Bromwich Albion, are already through to the last eight after winning 4-2 at Norwich City.
Fulham are due to host Arsenal tomorrow (Friday) night, while there are four ties scheduled for Tuesday including Leeds United v Manchester City.
The glamour tie of the round is next Thursday, when Manchester United host Chelsea.