Rugby World Cup 2015: Ireland's O'Brien banned for Argentina game

Sean O'Brien admitted punching France's Pascal Pape in Sunday's World Cup game in Cardiff

Ireland flanker Sean O'Brien will miss Sunday's World Cup quarter-final against Argentina after being suspended for a week.

The flanker, 26, was given the ban after admitting he punched France's Pascal Pape in the early stages of last Sunday's World Cup Pool D game.

O'Brien's ban is another major blow for Ireland with Paul O'Connell and Peter O'Mahony already ruled out by injury.

Fly-half Johnny Sexton is also an injury doubt for the quarter-final.

Team captain O'Connell, whose international career is now over as he is retiring from Ireland duty at the end of the tournament, sustained a serious hamstring injury in the France contest.

O'Mahony picked up a knee injury in Sunday's game and will also take no further part in the competition.

The normal sanction for O'Brien's offence is a two-week suspension but his ban was cut to a week because of his "remorse, good character and clean disciplinary record".

A World Rugby statement read: "O'Brien admitted committing an act of foul play and therefore the independent judicial officer Terry Willis upheld the citing. The Judicial Officer deemed the act of foul play merited a low-end entry point of two weeks."

O'Brien, man of the match on Sunday, will be available for the World Cup semi-final against either Australia or Scotland on 25 October if Ireland beat the Pumas.

Argentina centre Marcelo Bosch is banned for Sunday's World Cup quarter-final

Chris Henry and Jordi Murphy are obvious back-row replacements for O'Brien and O'Mahony although versatile Iain Henderson represents another option for Ireland coach Joe Schmidt.

Henry impressed when he came on for O'Mahony early in the second half against France while also Henderson starred after replacing O'Connell at half-time.

Rhys Ruddock could be another back row contender after being called up as a replacement for O'Mahony.

Argentina will be without centre Marcelo Bosch after he was handed a one-week ban for a dangerous tackle in last weekend's win over Namibia.

Bosch was a second-half replacement against Namibia after starting in the opening games against New Zealand and Georgia.