There were plenty of talking points on an enthralling opening day of the Rio 2016 Olympic Games men's sevens competition, none more so than Japan's history defeat of world champions New Zealand in their first match at the Deodoro Stadium on Tuesday.

The world's media were certainly eager to talk to Lomano Lemeki afterwards to hear his thoughts on Japan's 14-12 victory. 

“It’s unbelievable," he said. "You never see a minnow come here and beat a team that’s supposed to be a gold medal contender. I’m still in shock to be honest!

“I think we can (go all the way), especially after we just showed that any team can win at sevens, if we keep on working hard and playing like that.

“We had a game plan for New Zealand which was to keep the ball, if we got penalties to kick long, slow the ball down and play at our pace and they’ll get frustrated. We saw New Zealand starting to struggle there so we thought that if we kept moving the ball around, the big guys would tire and eventually they did."

Asked if New Zealand took them “softly” Lemeki replied: “I think they might have … but I don’t think they’ll be doing that again!"  

Things went from bad to worse after the loss to Japan, with coach Gordon Tietjens confiming that star Sonny Bill Williams won't be playing any further part in the Games, while Joe Webber is also unlikely to play again through injury.

"The squad is depleted, and it’s devastating for Sonny and also for Joe Webber. Both players worked their butts off to make this tournament and they're both influential players as well, with some outstanding qualities that I needed. But it wasn’t to be.

“There wasn’t much to say after the Japan game, it was disappointing obviously. We weren’t patient enough, we lacked accuracy and they’re a good team – they pushed Great Britain very closely as well. There’s no given games these days, but we have a chance tomorrow."

Their trans-Tasman rivals Australia also had a mixed day, losing to France in the first men's Olympic sevens match before beating Spain to stay in the hunt for the quarter-finals. Captain Ed Jenkins was understandably frustrated with the opening loss. 

“It was not ideal. We’ve been training really well. We definitely gave away way too much possession in that first half, so it always going to be hard to make our way back from 17-0 down.

“We spoke at half-time about tightening things up and not giving away so much possession and we came out with a few strong tries but they got one against the break of play and that pretty much put it out of reach.

“But we’re still in it, we’ve got Spain up and then South Africa so it’s not all doom and gloom – win these next two games and we’re through, so there’s still a lot to play for.”

France player Manuel Dall Igna summed up what won the game for Les Bleus: "Sometimes in rugby sevens, it’s very simple: possession is everything. The two times we didn’t have the ball, they scored, and the balls that we had, we found it difficult to score the first times but eventually we nailed it. We were more aggressive, more opportunistic."

Pablo Feijoo captured the hearts of rugby fans in June when he showed his emotion as Spain won the Monaco repechage to seal the last place at the Olympic Games. After their first match at Rio 2016 he was delighted with the occasion, but not overjoyed with the defeat by South African.

“It’s been amazing, it’s been a dream come true. But we know that to compete at that level we have to give 100 per cent and sometimes that’s not enough. Any mistakes and that’s a try against us. We knew South Africa would be tough.

“We have to be proud to be here but it’s not enough – we have to compete and do our best and if we can go into the last eight, great.”

South Africa coach Neil Powell added: “It’s always good to get the first match behind you, and to look forward to the second one – I think the guys will do better in the second one (v France)

“It’s good for us to get our momentum and lay a good foundation for the rest of the day. France have upset Australia so we’ll see how the pool goes, but it’s certainly interesting.”

Great Britain were the other unbeaten side on day one, having kicked off their campaign by running in five tries against Kenya, including a double for Dan Bibby who was delighted to finally be playing in the Olympic Games after the gruelling weeks of training in the run up to Rio.

“It’s great to get out there on the Olympic pitch. We’ve been together for 10 weeks now and we’ve been going hammer and tongs at each other and it’s nice to finally get out there and play against another teams rather than beating ourselves up ... and it’s nice to start with a win.

“We’re aiming for gold but we’ve five tough games to get there, and we’re taking it one game at a time and hope for the best."

Kenya’s Humphrey Kayange was part of the team who presented rugby sevens' case for inclusion to the International Olympic Committee in 2009 and, after his side's defeat by Great Britain, he admitted he was honoured to play in the Games.

“This is amazing. As far as what I wanted to do in sport, this is top of the list.

“It’s amazing playing with my brother (Collins Injera) and what an opportunity it is to run on the park together at the Olympic Games. For us it’s a very special bond to keep and a feeling you can’t explain."

With one loss to Argentina and a win over Brazil, the USA will still be in the hunt on day two, but speedster Perry Baker is not happy with the performances from his side. 

“I think we’re still feeling a bit nervous from all the atmosphere and we’re guilty of costly mistakes, but hopefully we got them all out tonight and we can turn around tomorrow.

“The competition has really stepped up a notch here at the Olympics, because of the whole atmosphere and everything. We’re feeling the pressure but the first two games are out of the way now so we have no excuses.

“We’re staying in the fight, we’re staying in the arm wrestle and we’re not giving up. Games are tight, games are tough and we’re staying here.”

In the last match of the day Argentina pushed HSBC World Rugby Sevens Series champions Fiji all the way before losing 21-14.

“Argentina is a good team and it was a very tough game," said Josua Tuisova, Fiji's opening try scorer."We were trying our best to make sure we could top our pool. We have USA tomorrow and it will be tough too, but we’d like to prove it to ourselves ahead of the quarter-finals."

Argentina captain Gaston Revol was upbeat after his side's defeat. “We were playing against the best team in the world but we did well, the boys played a great game. We’re a good team but we talked a lot about Fiji ... we need to focus more on our team and our game.”

Looking ahead to their final Pool A match against Brazil on Wednesday, Revol added: “Every time we play against Brazil, no matter what sport it is, we want to do our best so we will do it and we’re looking forward to a good show.”