Daniel Neilson upstaged fellow Britons Scott Brash and Ben Maher to come third in show jumping's London World Cup leg at Olympia.
Following a jump-off, he finished behind Dutch winner Maikel van der Vleuten and Belgium's Francois Mathy.
"This is a massive day. I couldn't have wished for any better," Neilson, who rode Varo M, told BBC Sport.
Brash and Maher are ranked first and second in the world but Brash came sixth while Maher missed the jump-off.
In the initial round of jumping, Maher had two fences down with Olympic horse Triple X and failed to progress.
"We're having one of those weeks right now, things aren't quite going right," he said.
Brash, who had four faults in the jump-off aboard Ursula XII, nevertheless assumes the overall World Cup standings lead by one point over Swiss Olympic champion Steve Guerdat.
The Scot is one of only two riders to have competed in all five World Cups so far this season. Five more events in the World Cup's Western European league remain.
In winning at Olympia, Van der Vleuten and VDL Groep Sapphire B repeated a feat achieved by his father, Eric van der Vleuten, in 2009.
"I was at home in front of the television and I saw him win. It's a dream to win a World Cup and I was very happy with my horse," said the younger Dutchman.
Essex rider Neilson, 23, said: "This is my first time at the show, my first time to jump at a World Cup, and I couldn't have wished for any better.
"There's no feeling like it when the crowd roars, it's great.
"If I can do what Scott [Brash] has done [in becoming world number one] that would be wonderful.
"What GB have achieved in the last few years is unbelievable. It's great for young riders like myself to see them push forward. It makes you want to achieve what they're doing as well."