The Frenchman has acknowledged West Ham's 'very positive results' at home and knows the north London side need to be looking over their shoulder.
And Wenger is fully aware of how tight the race for a place in next season's Champions League is becoming.
Wenger is quoted as telling reporters on Friday: "They [West Ham] are a threat. They’ve had very positive results at home. They went to Manchester United in the FA Cup and drew 1-1. Do Arsenal have to look over their shoulder?
"Yes, of course. It’s very tight. But I believe the Premier League is far from over. We also have to look behind us because things can change very quickly."
That means an Arsenal loss at Everton during Saturday's early kick-off gives West Ham the chance to leapfrog them when they travel to Chelsea later in the day.
Granted, Stamford Bridge isn't the easiest of places to travel - even this season - but there's no denying West Ham are right on Arsenal's tail.