Troy Parrott and Rodel Richards were on target as Tottenham U19s beat their Barcelona counterparts 2-0 away in the UEFA Youth League.
The result means that Tottenham have secured a second-place finish in Group B and will now go into the play-offs as they seek to make it through to the last-16.
With Inter Milan having beaten PSV earlier in the day, Tottenham knew they had to win to avoid elimination.
Tottenham opened the scoring in Spain with just 17 minutes gone, with Tariq Hinds bursting down the right flank and finding Edmond-Paris Maghoma, who in turn laid the ball on for Parrott, who slotted home.
Barcelona weren't at their free-flowing best but still managed to cause some problems for Tottenham in the first-half, most notably when Timothy Eyoma had to clear the ball off the line.
Fati came close to equalising for Barcelona in the second half, but the Tottenham defence managed to stand firm.
The visitors created numerous opportunities of their own, with Barcelona goalkeeper Arnau Tenas deserving immense credit for some impressive stops.
Tottenham then made sure of their victory in the closing stages, with Richards latching onto a loose ball to score with his first touch after entering the fray as a substitute.
Barcelona are through to the knockout stages as group winners but will be disappointed to have suffered their first European defeat of the campaign.
Tottenham, meanwhile, can be proud of a fluid performance in which they played some slick passes.