Fijian Drua's Frank Lomani was sent off in Friday night's Super Rugby Pacific clash after a shocking elbow to the back of his Melbourne Rebels opponent's head. 

Josh Canham was left bloodied after the match as Lomani faced calls for a lengthy stint on the sidelines for the brutal attack.

"Frank Lomani has had a brain explosion," Wallabies legend Tim Horan said on the coverage.

"He's now let his team down. They were just trying to claw back into the game and he gets a red card."

Lomani looked aggrieved after receiving the red card, despite it being an obvious send-off.

Elbows to the back of the head are banned in sports like the UFC due to the greater risk of permanent brain damage compared to strikes to the front of the head.

Teammate Jone Koroiduadua was also red-carded after he attempted to headbutt Rebels hooker Alex Mafi.

"There was definitely frustration there but that's no excuse. I apologise to the people back home for the two red cards, which were costly," Fiji coach Mick Byrne said after his side's 41-20 loss.

"The players need to find it in themselves to sort their discipline out if we want to get our season back on track."

In Friday's other match, a woeful Western Force have copped a thrashing, held try-less in a 50-3 belting by the Blues at Eden Park.

Force captain Nic White admitted his side hadn't turned up with the required intensity to match it with one of the competition's best packs.

"You've got to fight fire with fire sometimes and we lost what felt like the majority of our up-front battles," he said.

"We knew the contact zone was going to be important to us, we just didn't win enough of those.

"They're a big side — we know that, I think everyone knows that — a big powerful side. 

"We looked to move them around but we didn't do that enough."

AAP/ABC