Brentford's Under-17s lose on penalties against Club America in their Milk Cup Premier Section Globe Semi-Final.
Brentford looked to be in command as Clayton and Courtney Senior put The Bees 2-0 up in the first-half.
The South Americans grabbed one back before half-time and levelled things up five minutes into the second-half with a clever free-kick.
Reece Cole made it 3-2 from the spot, after Senior had been scythed down, before Clayton looked to have sealed the win when he netted his second, and fifth of the tournament, after 55 minutes.
As time ticked away the Mexican side began to throw bodies forward and Brentford could have wrapped things up two minutes from time but America managed to clear off the line.
That clearance proved to be decisive as America broke and made it 4-3 as the game entered injury-time.
The Bees were hanging on desperately, praying for the final whistle, but they were breached in the final minute of injury-time to send the game to penalties.
Club America hit the post with their opening penalty giving the advantage to The Bees but two-goal hero Clayton also struck the woodwork with The Bees fourth penalty to send the shootout to sudden death.
Chris Mepham saw his, and Brentford's eighth penalty saved, before America found the back of the net to spark wild scenes of celebration amongst the Mexican bench.
That defeat means Brentford will play Cherry Orchard from Dublin in the Globe Semi-Final tomorrow afternoon in Broughshane.