Arsenal took the lead in the 10th minute at Vicarage Road when Pierre-Emerick Aubameyang charged down Ben Foster’s clearance and the ball bounced into the back of the net.
Things then got worse for Watford when Troy Deeney was shown a straight red card for a reckless challenge on Lucas Torreira in the 11th minute.
Arsenal held firm through the second half and managed to claim all three points against the 10-man Hornets.
Celebrity Arsenal fan and former Daily Mirror editor Morgan was clearly delighted by what he saw from the Gunners as they moved back into the Champions League qualification spots.
Morgan wrote on Twitter: “FT: 1-0 to the Arsenal. Rare, vital away win thanks to a moment of brilliance from the flipping superb @Aubameyang7.”
The result lifted Arsenal back into the top four and level on points with Chelsea FC in fifth, who have played a game more than the Gunners.
The north London side are also two points ahead of Manchester United with five games left to play this season.
Arsenal will return to Premier League action on Sunday afternoon when they host Crystal Palace at The Emirates.
Before that, they will travel to Napoli for the return leg of their Europa League quarter-final clash on Thursday night, having won the first leg at The Emirates 1-0 last week.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news