Watford claimed local bragging rights with a 4-0 dismantling of near neighbours Luton in the Championship.
First-half goals from Keinan Davis and William Troost-Ekong set the tone and the visitors’ doom was sealed when goalkeeper Ethan Horvath gifted Joao Pedro a third before Ismaila Sarr completed the rout.
Hatters substitute Gabriel Osho then saw red late on for a dreadful challenge on Ken Sema.
Both games ended as 1-0 home wins two seasons ago, when Watford were promoted to the Premier League, but this was the first M1 derby watched by supporters since 2006.
Luton began a descent into non-league football soon after that but arrived at Vicarage Road as the form team thanks to seven games without defeat. Watford, in contrast, had lost three of their previous four.
The Hornets had been hard hit by injuries as well, including a broken leg at Millwall in midweek for midfielder Imran Louza, yet scored with their first attack, in the third minute.
Sarr played Hassane Kamara in on the left and Davis converted a cross into the six-yard box that was behind him with an impressive flick of a leg.
Allan Campbell fired an instant opportunity to equalise inches wide before Luke Freeman sent a header straight at goalkeeper Daniel Bachmann.
Luton captain Sonny Bradley was booked for a hefty challenge on Pedro before Horvath had to get behind a deflected effort from Edo Kayembe.
Another chance to level disappeared 10 minutes before the break however when Elijah Adebayo, picked out by Freeman, headed over the bar.
It was to prove costly as although Horvath denied Davis a second with a block, Troost-Ekong made it 2-0 in added time. Davis and Sarr both challenged Bradley for a ball to the back post and it fell to the Hornets defender for a tap-in from unmissable range.
Bradley was replaced at the break by Osho, who scooped over a decent chance at the back post.
Again it was to prove a costly miss as Pedro made no mistake from Horvath’s dreadful error in the 57th minute. Davis put the goalkeeper under pressure and the American passed it straight to the Watford number 10, who only had to steady himself on the edge of the box and locate the net.
Davis had to go off injured for the final 20 minutes or so, with Bachmann denying Jordan Clark a consolation goal from a low drive.
Watford refused to let up and when Luton surrendered possession in their own half, Sarr eluded two challengers to slot in a 79th-minute fourth.
Luton’s discipline disappeared when Osho was shown a straight red for a touchline takedown of Sema seven minutes from time.
