Manchester City claimed the bragging rights over Manchester United with a 3-1 victory in an action-packed Women's Super League encounter at Old Trafford.
Katie Zelem fired the hosts in front from the penalty spot after Alex Greenwood was punished for handball, but a key decision went against United when Geyse's goal was disallowed because the ball was adjudged to have gone out of play.
City then turned the game on its head in the space of 80 seconds as Jill Roord fired home the equaliser before Lauren Hemp curled a superb effort into the top left corner after a mistake at the back.
Another error in the United defence saw Bunny Shaw gifted City's third as Mary Earps' clearance ricocheted off the striker and into the net.
City looked set to cruise to victory until Laia Aleixandri was shown a second yellow card prompting United to throw on several attackers in a bid to force a comeback although goalkeeper Khiara Keating only had to save a long-range drive from Lucia Garcia.