West Ham are into the Europa League knockout stages despite a late Tomas Soucek own goal that saw them draw with Genk in David Moyes' 1,000th match as a manager.
Moyes has garnered more than enough experience in his almost 24 years in the dugout to know sentiment counts for nothing and his side had to come from a goal down in Belgium.
The Hammers had paid for a slow start at Cegeka Arena, with Joseph Paintsil darting onto Junya Ito's pass and goalkeeper Alphonse Areola unable to keep out the forward's low strike.
Benrahma fired in from Vladimir Coufal's smart pull-back to level after the break and then added a delightful individual effort eight minutes from time to seemingly wrap up a win.