Young striker Mitchell Duke came off the bench to fire Central Coast to a come-from-behind 3-1 victory over Adelaide and extend their lead atop the A-League.Duke scored twice in the second half to turn what had been a frustrating match for the Mariners in front of 8294 fans at Bluetongue Stadium.Despite dominating the first half, the home side trailed 1-0 at halftime after Reds defender Daniel Bowles' scored against the run of play.But Duke's performance, and an inspired substitution by Graham Arnold, ensured Central Coast moved six points clear of second-placed Adelaide.Midfielder Michael McGlinchey sealed the win with a goal in the 89th minute.Celtic-bound playmaker Tom Rogic was officially farewelled at halftime and life after the young playmaker won't be looking quite as dim following the performance of 22-year-old Duke.He entered the game in the 61st minute in place of Oliver Bozanic and needed only six minutes to pull the Mariners level.The Reds failed to defuse a Nick Montgomery cross and Duke was on hand to poke the ball home for his second A-League goal.Duke was again involved a short time later as his cross was handballed by Bowles in the box and referee Peter O'Leary pointed to the penalty spot.League top scorer Daniel McBreen stepped up but had this spot kicked denied by a brilliant diving save from Eugene Galekovic.The miss was quickly forgotten, though, when Duke gave the Mariners the lead in the 72nd minute with a fine solo effort.Remarkably, Adelaide took a 1-0 lead into halftime despite being totally dominated by the Mariners.The home side's best opportunities came in a frantic three-minute period, with Bernie Ibini hitting the side netting from a dangerous McBreen ball in the 16th minute.Ibini then made a spectacular run into the box two minutes later before Bozanic scuffed a shot, allowing Galekovic to stop it from point-blank range.Adelaide almost stole the lead against the run of play in the 36th minute through Jeronimo Neumann but they did so three minutes later.Bowles' long-range shot took a deflection off Bozanic and Mariners 'keeper Mat Ryan could do little as it went in off the left upright.Arnold was delighted with the performance, comparing it to the Mariners' 7-2 thumping of Sydney FC earlier this season."It was up there with our best (performance) of the season," Arnold said."I think if we were more clinical in front of goals, you could have had another Sydney FC score. We had that many chances."I think the boys really stepped up tonight and set their own standards again and they have to maintain them."Arnold was full of praise for Duke, who started in the season opener but has struggled with an ankle injury since."Over the last few week he's been getting back to his best," Arnold said."I just said to him 'it's your night, tonight. No one else has been able to put it in, so put it in' and it was two great finishes."Adelaide coach John Kosmina admitted his side was simply outplayed."There's a reason they're top and we're not - they're a good side," Kosmina said."Having said that, we turned the ball over way too cheaply."If you keep doing that you're going to build pressure on yourself and eventually you're going to start to feel the pinch."