Defending champions New Zealand, HSBC World Rugby Women's Sevens Series 2018 winners Australia, France and hosts USA will contest the Championship semi-finals after a day of hugely entertaining play at Rugby World Cup Sevens 2018 on Friday.
The 16 women's teams got the action underway at AT&T Park, home of the San Francisco Giants Major League Baseball team, with the innovative new 'knock-out' format meaning sides have to win every match to be crowned World Cup winners.
The Championship semi-finals will get underway at 11:42 local time (GMT-7) on Saturday with New Zealand facing USA and Australia taking on France.
Fiji and Spain had the honour of opening the tournament with Las Leonas edging a tight battle 19-12 to set up a Championship quarter-final with Australia, the Olympic champions getting their campaign off to a winning start against debutants Papua New Guinea with Charlotte Caslick scoring two of their six tries in a 34-5 victory.
The two sides had met at the same stage at RWC Sevens 2013 in Moscow with Spain ending Australia's title defence, but there was to be no repeat of that upset with Evania Pelite scoring a hat-trick in a comfortable 34-0 victory.
New Zealand were in sublime form in both matches in San Francisco, captain Sarah Goss scoring the tournament's first hat-trick in a 57-0 defeat of first-time RWC Sevens participants Mexico in the round of 16 before powering past Ireland in the Championship quarter-finals, Michaela Blyde crossing for three tries in the 45-0 win to end the day on top of the try charts with five.
Ireland had earlier beaten England, seeded one place above them in eighth, with Amee Leigh Murphy Crowe's second try proving the difference as her side held on to triumph 19-14 and condemn their rivals to a finish of no higher than ninth place for the second RWC Sevens running.
That match was the only one to go against the seedings in the round of 16 with 2013 runners-up Canada, hosts USA, Russia and France all keeping themselves in the race to lift the coveted trophy on Saturday evening in San Francisco.
If the first two quarter-finals were straightforward affairs for New Zealand and Australia, the third between Canada and France was a nail-biting affair that swung one way and then the other, Les Bleues racing out of the blocks with tries by Majorie Mayans and Lina Guerin only for Canada captain Ghislaine Landry to touch down on the stroke of half-time.
A great solo try by Charity Williams edged Canada ahead for the first time before Guerin and Bianca Farella traded scores to leave the sides locked at 19-19. Extra-time seemed on the cards until Coralie Bertrand, the rookie of the year on the 2018 series, managed to reach out for the winning try to spark wild celebrations among her team-mates given it secured a first-ever RWC Sevens semi-final.
Two first-half tries by Naya Tapper then looked to have crowd favourites USA on their way to victory over Russia with a 21-5 half-time lead, but the Europeans battled back to within a score before quick-fire tries by Ilona Maher and Cheta Emba made certain of a semi-final showdown with defending champions New Zealand.
Meanwhile in the Challenge quarter-finals England, Fiji, Japan and China bounced back from their opening losses to ensure a top 12 finish. The semi-finals will get underway at 10:14 local time with England facing China and Fiji taking on Japan.
Before then, Mexico will tackle South Africa and Papua New Guinea will Brazil in search of their first win of RWC Sevens 2018.