Petr Cech admits Arsenal were handed a 'huge setback' ahead of their crunch meeting with Chelsea at the weekend as Watford left the Emirates Stadium with all three points on Tuesday night.
The Gunners were shocked as their visitors raced into a two-goal lead courtesy of Younes Kaboul and Troy Deeney.
Alex Iwobi hit back for Arsenal at the start of the second half but Arsene Wenger's men could not find another goal to share the spoils and instead the 2-1 defeat now leaves them nine points behind Premier League leaders Chelsea.
A tough trip to face Antonio Conte's Blues is next up, with a defeat at Stamford Bridge not only meaning Arsenal would be 12 points adrift of the summit but also with the possibility of being outside of the top four.