* Arsenal beat West Ham 3-1 at Emirates stadium
* Arnautovic gave West Ham a 25th-minute lead
* Monreal equalised on the half-hour mark
* A second-half Diop own goal fired Arsenal ahead
* Substitute Welbeck sealed the win in stoppage time
* West Ham host Wolves next, Arsenal visit Cardiff
ARSENAL 3 WEST HAM UNITED 1
Aug 25 (Reuters) - Arsenal celebrated their first Premier League win of the season under new manager Unai Emery after coming from behind to beat London rivals West Ham United 3-1 in an action-packed match on Saturday.