Reigning English Premier League (EPL) champions Chelsea have lost 1-4 to Watford, their second straight EPL defeat and the hosts' first triumph of 2018.
The decision by new Watford coach Javi Gracia to advance his lines created enormous problems for Chelsea here on Monday evening, reports Efe news agency.
Chelsea's stumbles in their own end created openings for Richarlison and Gerard Deulofeu, playing for Watford on loan from Barcelona, and the pressure pushed Chelsea midfielder Tiemoue Bakayokoto to commit fouls that saw him sent off in the 30th minute for a second yellow card.
With his side down to 10 men, Chelsea goalkeeper Thibaut Courtois came out against an onrushing Deulofeu and drew a foul. Troy Deeney stepped to the line and made it 1-0 for the hosts in the 42nd minute.
Though Chelsea made adjustments, it took them until the 82nd to pull level, thanks to an outstanding individual effort by Eden Hazard.
And instead of signalling a Chelsea comeback, the equaliser turned out to be the prelude to a Watford onslaught that produced three goals in less than 10 minutes.
Daryl Janmaat struck first, in the 84th minute, followed in the 88th by Deulofeu, while Roberto Pereyra delivered the final blow in stoppage time.
Chelsea, with 50 points from 26 matches, are in third place, trailing Liverpool by a point. Watford climb to 30 points and sit 11th on the EPL table.