'Redemption': Katoa's drive to keep firing for Tonga

But firing into the World Cup arena with a 30-12 monster win over the English has given the playmaker a chance to atone for past failings.

"I felt like my last couple performances in the Tongan jersey was pretty poor ... so for me it was a bit of redemption," Katoa said.

"Nothing personal to England, I just want to have a better performance to make our nation proud."

The win may have surprised outsiders, but those inside camp always believed in their potential.

"Within our four walls, we had that belief already," the 22-year-old said.

"We understand the potential of this group and I think internally we've just got a bit of a quiet confidence about us."

Injuries could pose a barrier to Tongan success, but the team rallied and overcame the loss of five-eighth Latu Fainu just 17 minutes into their opening game.

Initial fears pointed to a potential pectoral tear, but the injury to the Wests Tigers half is now considered far less severe.

Fainu was back training on Tuesday in Sydney and is hopeful of playing Friday against Lebanon.

Katoa on the other hand was preparing separately from his teammates after picking up an injury in the Dolphins' finals loss to the Sydney Roosters.

After another knock to the same ankle, Tonga are being cautious with their star playmaker.

"It was more just precautionary," Katoa said of training alone.

"I kind of bumped it again on the weekend, very early stages in game so it's more so just to manage my load."

After leaving the preliminary final in a moon boot there were grave fears he would miss the entire World Cup, but the Dolphins' medical team worked tirelessly to make sure he was available.

"I snuck off in a moon boot ... and I was in a fair bit of pain after the (Roosters) game," Katoa said.

"I can't thank our Dolphins medical team enough.

"It was our two weeks off, it was their break as well, but a lot of them were coming in on their days off."