Gareth Thomas will become the first Welshman to win 100 caps when he leads the team out against Fiji on Saturday.
Thomas has overcome his rib injury to lead Wales
The Wales skipper has recovered from a rib injury to play at full-back in the World Cup Pool B quarter-final decider.
Dwayne Peel has held off pressure from Mike Phillips to start at scrum-half, with Stephen Jones and James Hook continuing as the 10-12 partnership.
Lock Ian Evans will make his first start this year after proving his fitness as a replacement against Japan.
Evans joins Ospreys team-mate Alun Wyn Jones in the second row as coach Gareth Jenkins makes seven changes to the side that beat Japan in Cardiff last Thursday.
Full-back Thomas, wing Mark Jones and centre Tom Shanklin return to a strong-looking backline, while prop Gethin Jenkins and hooker Matthew Rees join Evans in coming into the pack.
Peel's position at scrum-half had been under scrutiny since Phillips, who is often likened to Wales great Terry Holmes, produced a sparkling performance against the Japanese.
He had also replaced Peel during the two previous matches against Australia and Canada, with Wales great Gareth Edwards saying the Ospreys man should start against Fiji in Nantes.
But Peel, who captained Wales in their first pool game against Canada, has been given the nod to win his 58th cap.
No side would want to go into a game of this magnitude without its captain, it's as simple as that
Wales coach Gareth Jenkins
Captain Thomas has made a quicker than expected recovery from the rib injury he sustained against Australia, which had threatened to end his international career.
But Jenkins feels Thomas' presence will be vital in this must-win encounter, having enough confidence in his captain's fitness to go without a recognised full-back on the bench.
"No side would want to go into a game of this magnitude without its captain, it's as simple as that," said Jenkins.
"Gareth's importance to this team cannot be understated, he's reached an historic landmark but no-one will be more focused than him on match day.
"His stature and composure on the rugby field will be invaluable to us in a game that could offer us such high rewards."
Back-rower Jonathan Thomas (finger), centre Sonny Parker (groin) and prop Adam Jones (foot) are still recovering from injury.
The winners of the match will advance to a quarter-final meeting with South Africa in Marseille's Velodrome on Sunday, 7 October (1400 BST), the losers having to go home.
Wales team to face Fiji at the Stade La Beaujoire, Nantes, on Saturday, 29 September (1600 BST):
G Thomas (Cardiff Blues, capt); M Jones (Llanelli Scarlets), T Shanklin (Cardiff Blues), J Hook (Ospreys), S Williams (Ospreys); S Jones (Llanelli Scarlets), D Peel (Llanelli Scarlets); G Jenkins (Cardiff Blues), M Rees (Llanelli Scarlets), C Horsman (Worcester), AW Jones (Ospreys), I Evans (Ospreys), C Charvis (Newport Gwent Dragons), M Williams (Cardiff Blues), A Popham (Llanelli Scarlets).
Replacements: TR Thomas (Cardiff Blues), D Jones (Ospreys), I Gough (Ospreys), M Owen (Newport Gwent Dragons), M Phillips (Ospreys), J Robinson (Cardiff Blues), D James (Llanelli Scarlets).