It was only Southampton's fourth defeat of the campaign and knocked the long-time leaders and FA Youth Cup semi-finalists off the top of Group A in the FA Premier Academy League.
Jacques Maghoma (pictured) lobbed home off the crossbar for what turned out to be the winning goal in the first half.
Here is coach Pat's report. "It's our best result of the season, without doubt, although I wouldn't describe it as the best performance.
"SOUTHAMPTON ARE A STRONG SIDE, THEY'VE BEEN RUNNING AWAY WITH THEIR SECTION AND THEY’VE BEEN THAT WAY OVER THE LAST THREE OR FOUR SEASONS.
"In fairness, I felt we started a little shakily and for the first 10 minutes we were under the cosh a little. Gradually as the game wore on we got more confident, started to get behind them and then scored.
"They goal came against the run of play and it was a strange goal, a ball over the top that Jacques Maghoma beat the keeper to, his effort hit the crossbar and the keeper somehow took it over the line.
"That gave us a lift and within five minutes Jamie Davis went through with just the keeper to beat and put it the wrong side of the post and then Jacques played it across and we missed from close range.
"So although we hadn't dominated the first half we had the three best chances of which one went in.
"We couldn't get hold of the ball as well as we did in the first half in the second half and it was a real battle.
"We defended well, battled away and then created another couple of chances that would have been good goals - Jacques again cut in from the left, beat a couple of players but didn't get enough power in his shot and then David Hutton did exactly the same, cut inside, skipped past a couple of defenders and then hit a tame shot.
"It was a really good victory and I was really pleased for them."
Spurs U18s: Button, Smith, Martin, Lewis, Mills, Peprah, Davis, Wells, Hamed, Maghoma, Hughton (Hutton, 70). Unused subs: Lake, Stroud, Hutchins.