Crystal Palace's Dean Benamar tussles with Manchester United's Junior Brown in the Premier League U18 cup final at Selhurst Park [Getty Images]Darren Fletcher's decision to swap his goalkeepers for the penalty shoot-out backfired as Crystal Palace lifted the Premier League Under-18 cup by beating Manchester United 6-5 on spot-kicks.United thought they had won it as they led with the game in stoppage time thanks to Noah Ajayi's first-half effort.However, the entire contest turned on its head as Palace striker Ben Casey, who had already gone close twice earlier in the contest, got the wrong side of the visitors defence, and Albert Mills panicked and brought him down.Casey drove home the equaliser from the penalty spot, with Mills watching on in despair from the mouth of the tunnel in the corner of the stadium, his dismissal forcing United to play through extra-time with 10-men.United held firm for the additional 30 minutes, although it needed a brilliant save from Cameron Byrne-Hughes to keep Palace out.Byrne-Hughes has been first choice all season but with two minutes of injury-time shown, Fletcher elected to bring on Shrewsbury-born Freddie Heath, who went to Maynooth with the senior squad earlier this month for the four-day training camp.Sadly for the visitors, Heath was unable to get near any of Palace's penalties and, in sudden death, Lucca Benetton's save from Godwill Kukonki proved decisive.United, who beat Palace in the FA Youth Cup last Friday, to set up a final clash with Manchester City, only had themselves to blame.They had numerous chances to get a second, with Chido Obi hitting the bar with the best opportunity, while Jay McEvoy also failed to convert a glorious chance to win it in extra time.