FIJIAN centre Seremaia Bai said he was willing to try to fill the hole left by the injury to star playmaker Nicky Little when the Pacific Islanders take on South Africa tonight (Sydney time).

Little, who had been instrumental in Fiji's shock 38-34 pool win against Wales, scoring 18 points, strained his knee ligaments in that game, which ruled him out for the quarter-final against the Springboks.

The glaring vacancy at No.10 will be filled by either Bai or 22-year-old Waisea Luveniyali, who played five-eighth in the 55-12 loss to Australia.

Bai, who plies his trade with French first division club Clermont but has also spent time playing in Australia, Japan, New Zealand and Wales, said Little's absence would hit Fiji hard.

"We'll really miss Nicky, he's been playing so long for Fiji," he said.

"We have to be organised as Nicky has been playing in that position over many years. He's world class."

However, Bai insisted that not much would change despite Little being ruled out of Fiji's biggest game against one of the tournament favourites.

"We have to stick to the game plan," said Bai, who will likely take over kicking duties, having successfully amassed 107 points in 29 Test matches for Fiji.

"At the moment, South Africa are the form side of the competition - big forwards, fast backs. But now that we have reached our goal of making the quarter-finals we want to go higher."

Bai added that his team had been encouraged by the gripping performance fellow islanders Tonga turned in against South Africa, which the Boks eventually won 30-25 after bringing on several first-teamers in the second half.

"We saw the South Africa game against Tonga, and the way Tonga played gave us positive ways to play," he said. "We know the South Africans are beatable - they only have two arms and two legs."

Fiji's forwards coach Joji Rinakama said the decisive element of the game against South Africa would be up front.

"They are always aggressive," he said of the Boks. "The key for us will be the set piece.

"We had 39 per cent possession against Japan - and we won the game. We had 41 per cent against Canada - and we won the game.

"Against Wales we won 100 per cent of our lineouts and had 50 per cent possession, so if we can secure 50 or 60 or 70 per cent [possession] on Sunday, we can beat them."