Watford striker Odion Ighalo struck for his side just minutes into the second half of their FA Cup clash with Arsenal at the Emirates.
With both sides struggling to get anything on target in the first half, the pressure was certainly building on the hosts who are eyeing a third consecutive FA Cup triumph.
Despite playing some impressive football, the Gunners were unable to find a breakthrough with Mohamed Elneny guilty of missing some excellent opportunities.
Arsene Wenger’s side were made to paid for their lack of decisiveness in the final third with Ighalo finding the back of the net just four minutes after the interval.
After Troy Deeney had won the initial flick-on, his fellow striker did brilliantly to hold Gabriel off before swivelling and sending an arrowed effort beyond David Ospina to silence a stunned Emirates.
Wenger can ill-afford another defeat on Sunday, as the Frenchman is already under fire following a poor run of form which has seen them fall eight points off the pace in the Premier League title race, as well as slipping to a two-goal deficit ahead of their second leg clash with Barcelona in the Champions League.