IRELAND's James Collins came off the bench for Luton Town to score with his first touch as the Hatters beat arch-rivals Watford at Kenilworth Road for the first time since 1993.
The Hatters, who were the better side for long periods, were awarded a penalty with 18 minutes to go, as Collins came off the bench to send keeper Daniel Bachmann the wrong way and net the only goal of the game.
The result dealt Watford's automatic promotion hopes a blow, but Swansea and Brentford could only draw in the chase to win promotion behind Norwich.
Swansea were forced to claw their way back from two goals down to claim a 2-2 draw against bottom-of-the-table Wycombe to keep alive their slim hopes of challenging Watford for the second automatic promotion spot.
However, the point Steve Cooper's side were able to scramble late on cut the gap between second and third to six points.
Brentford also wasted the chance to gain ground on Watford with a 0-0 stalemate against Millwall.
Meanwhile, Hull are two wins away from automatic promotion back to the Championship.
Second-half goals from Josh Magennis and Keane Lewis-Potter against Fleetwood put the Tigers 11 points clear of third-placed Sunderland - who they host in midweek - and 13 ahead of fourth-placed Lincoln - who have two games in hand and welcome Hull next Saturday.
It leaves City needing two wins from their final four games to guarantee promotion back to the Championship at the first attempt.
Sunderland's automatic promotion hopes suffered a big blow following a 1-0 defeat at Blackpool.
Luke Garbutt scored the only goal of the game with the aid of a deflection just before the hour mark.