Republic of Ireland forward Leanne Kiernan curled home a brilliant strike to help West Ham to victory against Lewes FC in the Continental Tyres Cup on Sunday afternoon.
The Cavan 19-year-old joined the FA Women's Super League side in July having shone for Shelbourne.
Danielle Lane put Lewes ahead at Rush Green Stadium but the hosts levelled through Jane Ross before Kiernan fired them ahead via the underside of the bar.
Julia Simic made it three before half-time, with Ross slotting home from the spot after the break to warp up the win.
The move to London has given the prolific Kiernan a first taste of professional football and she has hit the ground running.
Last week she set up the Hammers' only goal in a a 31- loss at Arsenal, for whom Ireland captain Katie McCabe scored twice.