Fulham's relegation from the Premier League was confirmed with a 4-1 loss to Watford at Vicarage Road.

Will Hughes, Troy Deeney and Kiko Femenia struck as the Cottagers crumbled in the second half and were left 16 points adrift of safety with just five games remaining.

Fulham invested close to £100million in its squad after achieving promotion from the Championship via the play-offs last season, but its immediate return to the second tier was sealed after a ninth successive loss.

Ryan Babel cancelled out Abdoulaye Doucoure's first-half opener but a tactical shift at half-time from Javi Gracia made the difference, with Watford running away to a comfortable triumph ahead of its FA Cup semi-final against Wolves on Monday (AEST).

Fulham started the game positively but fell behind in the 23rd minute when Maxime Le Marchand invited Doucoure to shoot and the midfielder duly fired beyond Sergio Rico from 18 yards.

Cyrus Christie saw a cross tipped against the bar before Babel showed tremendous composure to round Ben Foster in the 33rd minute.

Joe Bryan's cross hit Hughes's arm in the box before half-time but nothing was given and in a bid to halt Fulham's momentum Gracia switched to a three-man defence for the second period.

Ryan Sessegnon wasted a great opening and Fulham was punished when Le Marchand's attempt to clear a corner was emphatically volleyed past Rico by Hughes in the 63rd minute.

Fulham's resistance was broken and Andre Gray, who replaced Gerard Deulofeu at the break, did superbly to tee up Deeney six minutes later.

Femenia delivered the final blow 15 minutes from time when he guided home another pass from Gray at the end of a swift counter-attack that caught Fulham short.