Today, Japan player Lomano Lemeki described the latest feat as "unbelievable" after New Zealand, who also lost star player Sonny Bill Williams to a tournament-ending injury, were floored.

Japan took an early lead through a try from Teruya Goto that Lemeki converted, but that was the cue for an immediate response.

Scott Curry and Akira Ioane collected touchdowns either side of half-time, but Japan would not buckle and they secured a famous victory through Kameli Soejima's try that Katsuyuki Sakai converted.

"It is unbelievable," Lemeki said.

"You never see a minnow come here and beat a team which is supposed to be a gold medal contender. I am still shocked, to be honest.

"As we played on, we started getting more confident and New Zealand started to struggle a bit.

"We thought if we kept moving the ball around, the big guys would tire somewhere, and they eventually did.

"We had a game plan against New Zealand - play at our pace, and they would get frustrated."

Great Britain and Kenya are also in Japan's group, and asked if his team could progress deep into the three-day tournament, Lemeki added: "I think we can, after we showed that any team can win.

"We need to keep working hard, and I am sure we will."

A thrilling opening round of fixtures also saw a highly-fancied United States team lose 17-14 to Argentina, while Australia came unstuck 31-14 against France.