Jack Carty will start at fly-half as Ireland head coach Joe Schmidt makes four changes for his side's Pool A match against hosts Japan on Saturday.

Johnny Sexton is not included in the squad, having been taken off in the win over Scotland with a thigh niggle.

Rob Kearney and Keith Earls return to the back three as Jordan Larmour and Andrew Conway make way.

Chris Farrell partners Garry Ringrose in midfield as Peter O'Mahony is fit to start in the back row.

Centre Robbie Henshaw is again not included in the matchday 23 having picked up a hamstring injury in the first week of training in Japan.

However, Joey Carbery is set to return to action as he is named on the bench following his recovery from an ankle injury sustained in Ireland's first warm-up game against Italy in August.

Twenty-seven-year-old Carty made his international debut as a replacement against Italy in this year's Six Nations.

The fly-half followed up a strong season at Connacht with an impressive showing in Ireland's warm-up games, including a man-of-the-match display against Wales in Cardiff.

Sexton relinquished place-kicking duties during the first half of Ireland's 27-3 victory over Scotland but remained on the field until the 59th minute.

There is no place for Bundee Aki, despite the centre being passed fit after coming off early against Scotland, although O'Mahony has recovered having gone through HIA protocol.

Schmidt has resisted the temptation to keep Conway and Larmour in the side after the duo performed well in Yokohama, and reverts to his favoured back three with Kearney and Earls joining Ulster wing Jacob Stockdale.

Japan bench captain Leitch

The hosts overcame a shaky start to secure a bonus-point win over Russia in the tournaments curtain raiser last Friday.

Captain Michael Leitch is a shock omission from the Brave Blossoms' starting XV to face Ireland.

Instead, head coach Jamie Joseph opts to bring fit-again Amanaki Mafi into the back row, with flanker Lappies Labuschagne taking over as skipper.

Mafi's inclusion for Leitch, which sees Kazuki Himeno move from the back of the scrum to blind-side flanker, is one of three personnel changes in the pack.

Koo Ji-won comes into the front row for Asaeli Ai Valu as Luke Thompson replaces Wimpie van der Walt at lock.

Wing Lomano Lemeki also makes way as Rhoyei Yamanaka comes in at full back with Will Tupuo moving to the left wing.

Ireland: Kearney; Earls, Ringrose, Farrell, Stockdale; Carty, Murray; Healy, Best, Furlong, Henderson, James Ryan; O'Mahony, van der Flier, Stander.

Replacements: Cronin, Kilcoyne, Porter, Beirne, Ruddock, McGrath, Carbery, Larmour.

Japan: Yamanaka; Matsushima, Lafaele, Nakamura, Tupou; Tamura, Nagare; Inagaki, Horie, Koo, Thompson, Moore; Himeno, Labuschagne, Mafi.

Replacements: Sakate, Nakajima, Ai Valu, van der Walt, Tanaka, Matsua, Lava Lemeki.