It was Iwobi’s second start for the Gunners after featuring in the team’s 2-0 win over Everton a fortnight ago and proved team’s coach Arsene Wenger right for starting him.
The Nigerian youngster scored in the 38th minute with a sublime cool finish to add to initial goals scored by Alex Sanchez and Hector Bellerin in the 4th and 38th minutes respectively.
Theo Walcott’s ensured the host garnered the maximum points with the fourth goal in the 90th minute as Arsenal keeps their title push alive.
Super Eagles striker, Odion Ighalo played the entire 90 minute as he could not rescued Watford from going down at Emirates.
Having scored 14 goals in the league, Ighalo had little chance to put the Gunners defence under pressure.