There were winning starts for the Hong Kong, China men's and women's squads on Friday as the Rugby Sevens got underway to much fanfare at the Kai Tak Sports Park.

The SAR men's representatives - who are looking to defend their Melrose Claymores title - cruised to a 31-7 victory over the national team.

"[We're] feeling pretty good, we went down early there, so we [had] good composure, good fightback to score some good tries out there," men's captain James Christie told RTHK after the win, who also credited the support of home fans at the stadium.

"You have to be here to witness it. It's nothing like I've seen before. Obviously [the fans are] the eighth man on the pitch, so it really helps us, inspires us."

They will look to keep their winning momentum going when they take on Japan on Saturday.

The women's side, meanwhile, held on for a 29-14 win over Kazakhstan in the opener. They will next face Thailand.

Co-captain Chloe Chan was confident that the squad can clinch the top prize, having finished as runners-up last year.

"We trained hard in and out every day," Chan said. "Once we're on there, it's all the same stuff – if we all do our job well, then we'll be okay."

The two matches were separated by an official opening ceremony featuring a dragon and lion dance, a performance by cheerleaders of South Korean baseball team Kia Tigers, and a laser show on the pitch.

Irish rugby legend Brian O'Driscoll and former Hong Kong winger Salom Yiu also made an appearance.

Outside the Melrose Claymores, 12 teams in the men's - and another 12 for the women's - fought to reach the knockout round.

Both the New Zealand men's and women's are aiming to defend their Hong Kong Sevens titles for a third successive year.

The women's squad, who are 12-time champions in the SAR, began the day with a 45-0 demolition of the national team.

"It was a really good game, and I thought we played pretty well," captain Sarah Hirini said after the match.

"[We] did some pretty cool things out there, and obviously very stoked to get a win like that against China who are a very quality team."

The Kiwis men's, meanwhile, also took care of business by beating Australia 21-12 in the opener.

Argentina, which fielded only a men's team, are also emerging as favourites. They were dominant on Friday, with big wins over Ireland and the United States.