A three goal blitz inside the opening ten minutes put the youngsters on their way to a deserved win on Saturday morning.
Saints took the lead with just four minutes on the watch when Luke Shaw's free-kick from the left was headed home by Jordan TURNBULL for the defender's fourth goal of the season.
Jason Dodd's side doubled their lead just three minutes later when Jake Sinclair was brought down on the edge of the area. SHAW (pictured) stepped up to curl a free-kick over the wall and into the back of the net to double the advantage.
It was 3-0 on 9 minutes with a breath-taking move that saw Chambers, Moore, Sinclair and Curtis all involved, as the ball eventually broke for Calum CHAMBERS whose left footed finish left the hosts stunned going into the interval.
Chelsea pulled one back in the second period when debutant Will Britt was denied a clean sheet on his bow when the home side converted a 73rd minute penalty, but it was too late to stage a comeback.
Saints were able to bring on Under-16s forward Ryan Seagar for his second appearance in the 18s squad, but the game was soured for the visitors who lost full back Fraser Colmer to a serious looking injury, who was uppermost in the players' thoughts after the game.
However, a first win in four was especially pleasing for Dodd, whose side closes the gap at the top of the table.
"I thought we thoroughly deserved to win," he said.
"We ran through things yesterday and the lads played it exactly as we hoped it would go. We were a little sloppy after the goals, but were comfortable and deserved winners.
"At half time we set them little targets including a clean sheet, but they managed the game well like we do at first team level, which is what it's all about."
Saints U18s: Britt, Colmer (Bowman 30), Mugabi, Turnbull, Shaw, Chambers, Gape, Moore, Curtis (Seagar 60), Rowe (Reed 60), Sinclair.