Javi Gracia hailed an "unforgettable" night for Watford as his side demolished 10-man champions Chelsea 4-1 in the Premier League in his first home match in charge.
Eden Hazard's leveller looked to have snatched a point for Chelsea at Vicarage Road on Monday despite Tiemoue Bakayoko's first-half red card before Daryl Janmaat, Gerard Deulofeu and Roberto Pereyra struck in the last 10 minutes for the Hornets.
Gracia's men moved six points away from the Premier League's relegation zone as a result of their first win against Chelsea in any competition since September 1999.
And the Spaniard, appointed as Marco Silva's successor last month, was thrilled to get off the mark with his first Watford win after a debut loss at Southampton and some raised eyebrows in England over his appointment as Watford boss.
"You always work for good nights like today but today has been unforgettable," Gracia told Sky Sports. "I'm very proud of my team and my players, happy for our fans and we had a great victory.
"I think we made a high press all match, not only after the sending off, we had many chances in the first half when we played better.
"In the second half we had more difficulties but when the match was level we scored the second goal and it was incredible, an unforgettable night."
Chelsea goalkeeper Thibaut Courtois accused Deulofeu of diving over his body to win a first-half penalty, converted by Watford captain Troy Deeney to give his side the lead.
But the Spanish winger, who arrived at Vicarage Road on loan from Barcelona last month, denied that he cheated referee Mike Dean into giving the decision.
"Daryl Janmaat gave me a good ball and I think it's a clear penalty," Deulofeu said. "He touched me, I think.
"We are happy for these three points, the team fight at the beginning and we are worth this win. I'm so happy for my first game at home."
And Gracia backed up Deulofeu, agreeing with Dean's call to give a penalty and to send off Bakayoko for a pair of fouls on Etienne Capoue and Richarlison inside five minutes.
"I didn't see it clear but I think the penalty is a penalty," Gracia added. "And yellow cards, I think the same."