An Elliot Lee double gave the Development Squad their first victory of pre-season at Havant & Waterlooville on Tuesday evening.
Lee struck twice inside the final eleven minutes to enliven a contest which took until the closing stages to find its first goal.
Bradley Bubb looked to have rescued a draw for the hosts when he cancelled out Lee's first with three minutes left, but the Hammers man hit back almost immediately to claim the spoils.
Mathias Fanimo fired wide of the Hawks' goal from 15 yards as the Hammers broke quickly early on, while at the other end Nathan Mavila made a fantastic last-ditch tackle to deny Josh Huggins.
The dangerous Djair Parfitt-Williams had West Ham's best chance before the break when he stepped inside his marker and sent a shot arrowing goalwards, only for keeper Ryan Young to save well.
Both teams made changes at the break and the game took a while to settle down. As the contest progressed, the Hammers began to see more and more of the ball and they eventually forced the breakthrough on 79 minutes when Lee wriggled his way out of a challenge on the edge of the box and sent a deflected shot into the net.
Bubb curled an effort into the net to bring Havant briefly level, but Lee was having none of it and restored the visitors' advantage when he got between defenders Harry Medway and Harry Woodford to slot the ball home.
Nick Haycock's side now head to Cambridge this weekend for the Absolute Travel Cup, which also involves teams from Shakhtar Donetsk and Espanyol.
*Meanwhile, George Moncur scored for his loan club Colchester United in their 8-0 victory over Heybridge Swifts on Tuesday night.
West Ham United: Howes, Pike, Mavila, Onariase, Burke, Makasi, Fanimo, Bailey, J.Brown, Gordon, Parfitt-Williams
Subs used: T.Brown, Maiga, Westley, Knoyle, Nasha, Pask, Oxford, Turgott, Bywater, Lee, Sadlier