Chelsea survived a real battle away to Crystal Palace to re-establish a five-point buffer between themselves and Manchester United.
For 30-odd minutes at Selhurst Park, Chelsea's garden appeared rosy after goals from Olivier Giroud and Christian Pulisic saw them cruise into a 2-0 lead.
Giroud's fifth Premier League goal of the season came from close range, after a Gary Cahill slip allowed Willian breeze through the Chelsea right and square for the handsome Frenchman.
Pulisic doubled their lead on 27-minutes. The American profited from some neat interplay between Willian and Giroud before conning Joel Ward and blasting past Vicente Guaita.
However, an Exocet missile from Wilfried Zaha 11-minutes before half-time dragged Palace back into the game.
Chelsea looked at last to be comfortable after a driving run from Ruben Loftus-Cheek set up substitute Tammy Abraham to make it 3-1.
But Christian Benteke's first goal since early February came as an almost immediate retort to make the last quarter hour incredibly nervy for Frank Lampard and co.
If Norwich didn't look doomed before their trip to Watford, they certainly do now.
Defeat to West Ham on Saturday will see Daniel Farke's side relegated to the Championship.
It all started so well for Norwich at Vicarage Road.
After just 6-minutes, Emiliano Buendia left Adam Masina twisting and turning before rifling past Ben Foster.
That joy was short-lived as Craig Dawson levelled for the hosts four minutes later.
But the best - at least from a Watford perspective - was saved for last.
An incisive run down the right from Ismaila Sarr saw him square the ball only for it to balloon up off the boot of Max Aarons.
Waiting in the centre was Danny Welbeck who acrobatically connected to beat Tim Krul in the Norwich goal.
The win sealed a massive three points for Watford who end the night four clear of the relegation zone.