Australia's defending gold-medalists got their campaign off to the perfect start with wins over Japan and China
Meanwhile, New Zealand had to avoid their own hiccups, requiring tries after the siren to remain unbeaten
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However, the biggest upset came in group B as Fiji defeated Canada, setting up an exciting day two.
RECAP ALL THE ACTION FROM DAY ONE BELOW IN OUR LIVE BLOG
ROC have overcome Kenya 35-12 to finish day one of action.
Nadezhda Sozonova scored first for ROC as they look to build off their strong performance against GB.
However, Kenya hit back with two tries of their own to bring it within two at the break.
In the end, two early second-half tries sealed the game for ROC, with the win sealed by Daria Lushina.
New Zealand have avoided a major upset, scoring four straight tries to steal victory from Great Britain 26-21
Great Britain opened the proceeding through Helena Rowland, racing out to a quick 21-0 lead.
Michaela Blyde would lead the comeback for the Kiwis, who were left shellshocked by GB.
Tyla Nathan-Wong closed the margin to just two with three minutes on the clock.
In the end, a yellow card to Jasmine Joyce changed the game as a last minute try to Blyde got them out of jail
The USA has set up a blockbuster match with Australia as they defeated Japan 17-7.
Iiona Mayer got USA off to a strong start as she powered through the Japanese defence, with Jordan Matyas crossing minutes later.
They would then turn defence into attack as Ariana Ramsey picked up the loose kick and cruised over.
Whilst Japan would score late, it wouldn't be enough as America secured the win, setting up a battle for top spot with the Aussies tomorrow
Australia has held off a gutsy China 26-10 to continue their unbeaten run
14': China score a consolation try, however, Australia secures the 26-10 win
10': Madison Ashby cuts through the line from the scrum for their fourth try.
8': Faith Nathan runs the length of the field as Australia extends the lead
6': Charlotte Caslick stretches the lead for the Aussies as she stays alive after setting up the break.
3': Sharni Williams immediately responds for Australia
2': China opens the scoring through Feifei Yang
France have powered to the top of Pool B with a 40-5 win over Brazil.
France dominated from the beginning, with Anne-Cecile Ciofani crossing for a double.
They would cruise home in the second half as Lina Guerin capitalised on a break from inside their half.
France would score two late tries to complete the dominant victory
Fiji has caused a major upset, defeating medal hopes Canada 26-12
They stunned Canada off the kickoff, scoring after just 14 seconds before extending the margin three minutes later through Ana Maria Naimasi.
Viniana Riwai followed her over as the Fijians took a 21-0 lead into the break.
Reapai Ulunisau burst through after the break to extend the margin and the win.
It would go from bad to worse for Canada with Keyara Wardley and Charity Williams coming off with injuries
New Zealand has cruised to a 29-7 win over Kenya.
New Zealand raced out to an early 17-0 lead as they scored three tries in five minutes.
Whilst Kenya hit back before the break, Michaela Blyde restored the margin as play resumed, shortly followed over by Grace Broughton to seal the win.
Great Britain has stolen victory at the death, scoring on the siren to defeat ROC 14-12
They recovered after a slow start, scoring through Abbie Brown to take a 7-5 lead into the break.
However, ROC refused to give up and found the lead with two minutes remaining via Kristina Seredina.
With the siren sound, Brown produced an incredible play to find the line as GB escapd with the win
Australia has sent a warning shot to the rest of the comp, dominating Japan 48-0.
14': Levi gets her double as Australia cruise to victory
11': Maddison Levi makes an instant impact on debut, scoring with one of her first touches
10': Tonegato finishes the hat-trick after another turnover from Pelite.
8': Hayes gets a double as they throw the ball around at will from the restart
HT': Tonegato scores her second on the siren as Australia take a 24-0 lead into the break
5': Tonegato bursts away and hands it off for Demi Hayes to score under the posts.
3': Emma Tonegato finishes off the move after Vani Pelite earns the turnover
1': Charlotte Caslick opens the scoring after just 40 seconds for Australia
USA has overcome a slow start to defeat China 28-14
Wanyu Wang shocked the Americans early on as they opened up their defence.
It took an individual piece of brilliance from Kris Thomas to turn the momentum as she ran 50 metres for the try.
The US would take the lead with four minutes remaining as Kristi Kirshe burst away for a quick fire double to seal the win.
Canada has cruised to a 33-0 win over Brazil
After a tense first half, Charity Williams found space on the wing and burst through the Brazillian defence.
Keyara Wardley would open up their defence after the break to extend their advantage.
Karen Paquin followed her over as she sliced through four defenders, with Ghislaine Landry and Wardley scoring shortly afterwards to seal the win.
France have held off a fast-finishing Fiji 12-5 to win the opening game of the tournament.
Fiji took advantage of a yellow card to French captain Fanny Horta as Viniana Riwai crossed for the first try of the match.
Horta would make up for her absence as she crossed before the break to give France the 7-5 lead.
France would extend their lead through Seraphine Okemba shortly after the break.
Whilst Fiji pressed their line late to tie it up, France held strong and came away with the turnover and the win.
The Women's Sevens side have been drawn in Pool C and will play against China, slated for 6:30 pm (AEST).
This comes after their dominant 48-0 win over Japan, headlined by a hat-trick to Emma Tonegato.
Their group stage matches will be rounded out against the USA on Friday, July 30 at 11:30 am
Australia's clash with China will be shown on 7mate at 6:30 pm
It will follow France's second match of the day, taking on Brazil.
The Seven Network has exclusive rights to broadcast every event of the Tokyo Olympics in Australia.
Events, including every game of the Rugby Sevens, will be shown on television across their three respective channels: 7, 7TWO, and 7mate.
They will also be live streaming their televised events via 7+ which will have a dedicated Olympics channel that can be accessed online or via the app.
