Manchester United wonderkid Shea Lacey picked up the first red card of his career in petulant circumstances as the Red Devils suffered more frustration against Brighton in the FA Cup. Old Trafford was left stunned by another abject performance from a star-studded cast, with teenage winger Lacey compounding their misery when he was dismissed in the final minute of the 90.Teenage forward Lacey made his senior debut towards the end of Ruben Amorim’s ill-fated reign at the so-called Theatre of Dreams. He was introduced off the bench in a 2-1 defeat at Aston Villa, with United looking to their fabled academy for inspiration once again.Lacey saw more game time in Darren Fletcher’s first game as interim boss, following the dismissal for Amorim early in 2026. The Red Devils’ U18 boss gave the youngster six minutes at the end of a 2-2 draw with Burnley.Fletcher has, unsurprisingly, continued to show faith in youth while filling a caretaker post. His twin sons, Jack and Tyler, were named on the bench for a cup clash with Brighton. Lacey was also given the nod.He was introduced much earlier against the Seagulls than he had managed against Villa and Burnley, with England international Mason Mount being replaced in the 62nd minute. United were looking for trickery and direct running on the flanks.Lacey provided that, as he quickly looked like the Red Devils’ most creative influence, but was unable to carve open opportunities as Brighton’s defence stood firm. He was cautioned in the 87th minute for a late tackle and knew that he was walking a disciplinary tightrope from there.Looking for smarter football bets? Get expert previews, data-driven predictions & winning insights with GOAL Tips on Telegram. Join our growing community now!That warning was not heeded, with emotion spilling over in the closing stages. Lacey disagreed with the award of a throw in the 89th minute and took to slamming the ball into the turf in disgust. That display of anger was not looked upon fondly by match referee Simon Hooper.Lacey paid the price for his act of aggression, with a second yellow card being flashed in his direction. That was followed by a red, leaving him to trudge through the Manchester rain and towards the tunnel. He was applauded from the pitch by a United fan base that still have high hopes for the Merseyside native.Add GOAL.com as a preferred source on Google to see more of our reportingThere were no cheers at the final whistle, with boos ringing out around Old Trafford following a 2-1 defeat for the hosts. Fletcher has not made the desired impact in the dugout, with no new manager bounce being enjoyed. United are now winless through their last four games in all competitions.They have slipped out of both domestic cups this season at the first hurdle, having suffered a humbling Carabao Cup defeat at League Two side Grimsby back in August. They have no European football on the agenda this term and sit seventh in the Premier League table, meaning that their hopes of landing major silverware have evaporated for another year.Lacey will hope to play a prominent role in future trophy quests, but for now he needs to learn quickly that petulance will not be tolerated at the very highest level. He will have to serve a ban before returning to the first-team fold, potentially under a third manager as United look to bring an interim boss through to the end of the 2025-26 campaign.