Rauluni will be joined by loose forward Mesake Davu and utility back Isi Nacewa, who have also been called in as cover for the Fijians who were injured against Japan.
The trio replaces Waisale Serevi, Sami Rabaka and Alivereti Mocelutu, who all suffered broken bones on Thursday.
Rauluni, the older brother of current squad member Moses Rauluni, was originally Fiji's first-choice halfback for the tournament but declared his unavailability and said he had effectively retired from international rugby.
The Titans No.9 played at the 1999 Rugby World Cup and has 43 Test caps to his name. He last played for Fiji against Tonga in July 2003, but hobbled off injured after just 12 minutes.
Auckland NPC player Isi Nacewa has been eyed all year as a possibility to fill the void of young fly-halves. He made his Auckland debut this season and scored the winning try for the Auckland Academy against the Fiji Warriors early in the year.
Davu last played Test rugby in November 2001 when he was one of the few standout performers on Fiji's disappointing tour of Europe. He has been a regular in the Fiji Seven team over the past year and helped the team earn a Gold Medal at the South Pacific Games in July.
Fiji coach Mac McCallion said Rauluni and Nacewa were automatic choices, but Davu was selected only after discussion with the captain Alifereti Doviverata and some other players.
McCallion added that Sydney-based Netava Tagi would have been the first-choice replacement had he been fit.
The three players are hoping to be with their countrymen by Tuesday, ahead of Saturday's crucial game against Scotland.