But there was otherwise plenty to cheer about for the fans at the Perth Sevens on a scorching Saturday after both the home teams went unbeaten on the way to securing semi-final berths.
The Australian women posted wins over Great Britain (54-5), France (26-12) and Canada (38-10) to set up a semi-final showdown with the US on Sunday.
The Aussie men broke a nine-match losing streak to NZ before going on to beat France 29-14 and Great Britain 24-21, setting up a final-four match-up against South Africa.
But the Australian men's win over NZ came at a big cost, with Cartwright forced off in the opening minutes with a shoulder dislocation.
Cartwright was given a green whistle for fast-acting pain relief and isn't expected to take any further part in the tournament.
The injury is a bitter blow to Cartwright, who has impressed in his first season of Rugby Sevens.
"It's tough, he shot out of the line and made a good shot," teammate Josh Turner said.
"That's the difficult part of our game - it's a full-contact sport.
"Carty's amazing. He's an incredible person.
"I just want to give a shout-out to his family - his grandma passed away last week.
"Carty's going through a bit at the moment, and I just wanted to send my love to their family."
Australia adapted beautifully to the 35-degree conditions, with the home side breaking NZ's spirits with the first two tries of the second half to open up a 21-7 lead.
"We're the fittest team out here," Turner said.
"We may not be the biggest, but when it gets to those 10 to 12 minutes (of a 14-minute match), we start coming back and we start really putting the tempo on teams.
"We were clinical, we finished a couple of good tries off, and we defended well."
The win over Great Britain was a nail-biter..
Australia led 19-0 before Great Britain scored three quick tries to go ahead 21-19.
But Australia came out on top after Hadley Tonga scored an acrobatic try in the corner after the final siren.
"It feels great," Tonga said.
"All the boys have confidence in me and my speed, so I'm very grateful to score that try in the corner."
Australia's last-gasp win meant NZ sneaked into the semi-finals at the expense of Great Britain.
The Australian women opened their account with an eight-tries-to-one hammering of Great Britain, with Heidi Dennis scoring a hat-trick.
It was a perfect way to bounce back from the 36-7 hammering Australia copped at the hands of NZ in the Singapore Sevens final last Sunday.
"I was a bit nervous ... but once we got rolling, it was great," Dennis said.
"It was a rough final in Singapore, but that's footy, you've got to move on.
"It was really important to get out here and start strong."
The ever prolific Maddison Levi scored one try in the win over GB, a brace in the France victory, and another two in their final group match against Canada.
