Fiji were left reeling with three players suffering suspected broken bones after their 41-13 win over Japan in Townsville.
Scrum-half Sami Rabaka, fly-half Waisale Serevi and blindside flanker Alivereti Mocelutu are all being examined by medical staff.
Fiji's media liaison officer, Charlie Charters, revealed: "There are three injuries with unconfirmed broken bones.
"Waisale Serevi has a broken right collarbone, Alivereti Mocelutu has a broken right forearm and Sami Rabaka has a broken metatarsal."
Coach Mac McCallion admitted he could be forced to call in re-enforcements should the injuries prove severe. "It was a big loss. It cost us tonight," said McCallion.
"I believe we have the depth to cover those possibilities. We might have to call outside Fiji for one of those places. We will decide that in the morning."
The victory effectively set up a decider against Scotland in Sydney on November 1 for the second spot in Pool B, and McCallion admitted there was still plenty to do before the South Sea Islanders could start to prepare for the quarter-finals despite receiving a confidence boost.
"We were relieved with the final result," he said. "We played a lot better than in our first two matches, but we have a lot of work to do before we meet Scotland. "This has given us a morale boost. This is what we needed to get back on track."
McCallion also paid tribute to the performance by Japan, who pushed his side all the way in the first half before tiring as the Fijians recorded 25 unanswered points.
"They've certainly improved," reflected McCallion "They've shown the world they can be a force to be reckoned with.
"It's pressure all the way. You're jumping up and down one minute, and your heart's in your mouth the next. We're just going to have to work on the ruck and maul."
Japan were left to reflect on the impressive second-half performance by Fiji, but Cherry Blossoms coach Shogo Mukai was disappointed his side's efforts after the break.
"The first half was as we had planned, we played really well," he said. "In the second half, Fiji did lots of long kicking and our forwards had to run back all the time. This exhausted our players.
"We made lots of mistakes in Fiji territory and gave away penalties which contributed to Fiji's big score.
"Also, Fiji's individual skills in running and their strength were especially notable."
Winger Daisuke Ohata added: "In the first half we played well and we played to our game plan. "In the second half we made to many mistakes and couldn't play our own game.
"If we look back at the Scotland and France games, this is our worst game so far."
Kiwi-born fly-half Andrew Miller reflected: "There are no excuses. I'm a professional player and I'm fit, but in the second half I was struggling a bit.
"When we had the ball there were not a lot of options and I made some poor choices."
Captain Takuro Miuchi preferred to look ahead to his team's final match against the United States on October 27. "We came to the game with a strong determination, but the Fiji players had strong skills and were strong players," he said. "We made a lot of bad mistakes."
"We have one game to go and we want to perform against the USA. We have played really well so far in the campaign; that is thanks to the Townsville people."
Fiji captain Alifereti Doviverata will, meanwhile, discuss with his family and team officials before deciding whether to return home over the weekend following the early birth of his daughter.
"She was born in the last quarter," Doviverata revealed. "A few hours before the game, Rosi .125his wife.375 rang to say she had pain, so it was on my mind during the match. "We were not expecting her today."
Fiji: Tries Ligairi 2, Tuilevu 2, Vunibaka; Conversions Little 2; Penalties Serevi, Little 3. Japan: Try Miller; Conversion Miller; Penalty Miller; Drop goal Miller.
FIJI: Ligairi; Tuilevu, Ruivadra (Vunibaka, 70), Rabeni, Delasau; Serevi (Little, 12), Rabaka (Rauluni, 51); Rasila, Smith (Gadolo, 74), Vetayaki (Seru, 70), Katalau, Leawere (Maimuri, 57), Mocelutu (Koyamaibole, 19), Sewabu, Doviverata.
JAPAN: Matsuda (Kubo, 74); Ohata, Parkinson, Motoki, Onozowa (Konia, 70); Miller, Tauji (Sonoda, 52); Yamamoto (Kurihara, 60), Sakata (Hasegawa, 60), Toyoyama, Kiso (Amino, 52), Parker, Okubo, Miuchi, Ito (Asano, 74).
Referee: N Williams (Wales).
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