Olivier Giroud scored a double as Arsenal overcame Stoke City 4-1 but the striker will be a West Ham fan for a day on Sunday.
Arsenal's victory moved them one point behind fourth-placed Liverpool, who still have to travel to London Stadium for a match against Slaven Bilic's side this weekend.
"Obviously we have to do the job. We have to focus on our games but to be honest with you I will be a big fan of West Ham tomorrow! They have all my support," the Frenchman told Sky Sports.
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Of Arsenal's performance at the bet365 Stadium, he said: "We were efficient up front and defensively were compact and defended well from the front.
"It's a great win and we've got two more finals to come.
"The most difficult thing against a team like Stoke is scoring the first goal and after that we had to be efficient."
