The young Hornets stung Cardiff City with a last gasp winner in their Professional Under-18 Development League match at the University College London Athletic Ground, Shenley.
Josh Rippon had equalised for the Bluebirds after 86 minutes, but substitute Enoch Muwonge scored Watford’s winner in the final minute.
City deserved better after battling back in spirited style against a Watford team who are top of the PDL under-18 division and earned 22 points from their opening 10 mate he’s this season.
Ntazana Mayembe scored the first goal of the match from a close range strike, netting after 35 minutes.
Dominic Hutchinson’s shot from long range flew into the top corner to make the score 1-1 soon after and the same player put Watford in front on 69 minutes.
That goal came against the run of play, but the Bluebirds showed great character to dominate and Rippon’s headed goal made it 2-2.
City dominated for long spells in the second half, but they suffered heartbreak when Muwonge shot past their Australian goalkeeper Jaimie Cogman.
The next under-18 fixture for Cardiff is against Bristol City at Cardiff Sports Arena next weekend.
Cardiff City u-18: Jaimie Cogman, Owain Pritchard, Sam Parsons (capt), Rubin Colwill, Josh Rippon, Eli King, Harry Pinchard, Ryan Kavanagh, Ntazana Mayembe, Isaak Davies, Siyabonga Ligendza (Kieron Evans 71). Subs: Tom Chiabi, Brad Stewart (gk), Taylor Jones, Frazer Thomas.