Alex Iwobi was substituted at the beginning of the second half as Arsenal claimed a 3-1 Premier League victory over West Ham at Emirates Stadium.
It was the Gunners first win of the English Premier League season and the Super Eagles star played his part in the success.
He was substituted in the 46th minute of action.
Marko Arnautovic gave the visitors a 25th-minute lead, with Nacho Monreal restoring parity five minutes later from Iwobi’s assist.
An entertaining and error-strewn contest continued to flow from end to end but an injury to Arnautovic robbed West Ham of their prime attacking threat before Diop erred.
Danny Welbeck came off the bench to gleefully blast in from close range, ensuring Manuel Pellegrini’s fledgling West Ham tenure stands at three defeats out of three.
Iwobi has scored one goal for the Gunners in the 2018/19 campaign.