The USA Under-20 side claimed the Junior World Rugby Trophy on home soil with a victory over Japan in the final to earn a place in next year's Junior World Championship in France.

By winning the tournament the USA are automatically promoted to the top flight of junior rugby, while Italy are relegated after finishing in last place in South Africa.

In perhaps the most exciting final in the tournament's history, the United States were able to hold off a desperate Japanese attack in the closing seconds to win 37-33 at a sold-out Murray Rugby Park, Utah.

The Brave Blossoms threw wave after wave of attacking runs at the Americans, hoping to find a break, but after about five minutes and a couple of dozen phases, they knocked on and the final whistle soon followed.

"That last minute, I've never felt so much pressure," said wing Kingsley McGowan. "You just had to want it. You just had to want it."

It was clear that both teams did and Japan, who were playing in their fourth straight close game, came up just a few metres short.

Japan believed they would win right until the end

"I believed until the finish that we would win," said Japan head coach Ryuji Nakatake. "They were so tough, mentally and physically, in the second half in the last 20 minutes. The players were great. It was a good challenge."

Japan held leads in the 44th, 55th and 61st minutes (there were a remarkable seven lead-changes in all) but couldn't just hold on. The Young Eagles' other wing Noah Tarrant, who had a hat-trick, scored what proved to be the winning try in the 76th minute.

"Their team was blitzing up a lot, so we just decided to swing it out," Tarrant said. "We knew we had daylight. It was a blessing to have daylight and just run for it."