World Rugby has brought in a tougher approach to dangerous tackling this year, with zero tolerance for reckless or accidental tackles that make contact with a players head.
Fiji coach Gareth Baber said Fijian players have grown up tackling a certain way and it can take time to make adjustments.
He said yellow cards have proved costly for them in recent World Series tournaments and it's something they've worked hard to address for this weekend's event in Las Vegas.
"When you get in the heat of battle obviously you fall back on your habit," he said.
"Giving less penalties away and keeping more people of the field will be a big bonus and we know that and the players know it, but it takes a while for some of those things to become habit forming.
"So we've worked hard on that but, as I say, we did some great stuff when we were in Sydney and Wellington and I want to see more of that again."
Fiji has slipped to third in the World Series standings, behind runaway leaders South Africa and England.
The Olympic champions kick off the tournament in Las Vegas against Japan tomorrow afternoon and are also drawn with Scotland and Australia in Pool D.
Photo: World Rugby / Martin Seras Lima (Fiji was knocked out early in Sydney).