Conor Sammon's 88th-minute goal saw Derby County grab all three points and end Watford's unbeaten home record at Vicarage Road this afternoon.
Jamie Ward put the visitors in front with a fine header before Fernando Forestieri levelled matters in the 11th minute with a deft finish.
Derby retook the lead with a Ward tap-in right on the stroke of half time but again Watford responded with a delightful Lewis McGugan curler.
Both sides had plenty of chances to win it but it was Derby who snatched three points when Will Hughes played in Sammon to poke past Manuel Almunia.
Below, Sports Mole casts its eye over an action-packed 90 minutes in Hertfordshire.
Match statistics:
Watford:
Shots 15
On target 3
Possession 55%
Corners 4
Fouls 18
Derby:
Shots 10
On target 5
Possession 45%
Corners 4
Fouls 11
Was the result fair?
Both sides had numerous chances but you have to say that Derby deserved the points mainly because of Watford's shocking defending. Their 3-5-2 formation often left them exposed at the back and the wasteful play at times was so poor that Zola may have do extra training on basic passing next week.
Watford's performance
The Hornets are known for their attacking prowess but won't go anywhere this season if they defend like they did. Ward was one of the smallest men on the pitch and was allowed a free jump for the first before sluggish play gifted Derby their second and third goals. Up front Forestieri took his goal well but it was Diego Fabbrini, playing just behind him, who provided the main threat for the hosts. Defensively, that might be the worst they play all season.
Derby's performance
Manager Steve McClaren has notched up two wins since officially taking over at Pride Park and in those two games they have scored six goals - not bad at all. Their record away from home is very impressive too as today's result sees them on four wins, a draw and a loss on their travels. They are a solid outfit in all areas of the pitch with no particular outstanding player. They could have had more goals today if they had found the right pass on the regular occasions that Watford left themselves short at the back.
Sports Mole's man of the match
Craig Bryson: Ward will win this award for many because of his brace but midfielder Bryson, who is having a great season, also shone. He set up both of Ward's goals and was a constant nuisance in midfield.
Biggest gaffe
Iriney's dilly-dallying on the ball allowed Derby to streak clear and score their second. The Brazilian did not have a good afternoon, picking up an early booking before giving away a goal and then being substituted after 55 minutes.
Referee performance
James Linington had a busy afternoon, dishing out six yellow cards. There was one moment when it looked like he had booked Adam Smith twice and not sent him off, but replays show that he actually cautioned John Eustace the first time when both men brought down Forestieri.
What next?
Watford: Next up for the Hornets is a trip to the South Coast to face Brighton & Hove Albion.
Derby: The Rams, meanwhile, welcome Birmingham City to Pride Park and will make it three wins in a row if they see off Lee Clark's Blues.