London - Star Irish flank Sean O'Brien will miss Sunday's Rugby World Cup quarter-final against Argentina after being suspended for a week on Tuesday.
His suspension deals another blow to Ireland's severely depleted ranks having lost captain Paul O'Connell and another outstanding flanker Peter O'Mahony to injuries suffered in the brutal 24-9 victory over France on Sunday.
There are also doubts over playmaker Jonny Sexton, who is struggling with a groin injury which forced him off in the first-half of the pool game which saw the Irish seal top spot and avoid a last eight meeting with defending champions New Zealand.
The 28-year-old O'Brien has been punished for punching France lock Pascal Pape in the opening seconds of the French match.
"O'Brien admitted committing an act of foul play and therefore the independent Judicial Officer Terry Willis (Australia) upheld the citing on the basis that the player had committed an act of foul play," read the statement from the organisers.
"In the context of the Rugby World Cup tournament a week equates to one match.
"The suspension takes effect immediately, therefore O'Brien is suspended for Ireland's quarter-final match against Argentina on Sunday, 18 October, 2015. He is free to resume playing on 19 October, 2015."
O'Brien - who was named man of the match - could have faced a two week suspension but the adjudicating officer found that there were factors in O'Brien's favour.
"With respect to the sanction, the Judicial Officer deemed the act of foul play merited a low-end entry point of two weeks," read the statement.
"The Judicial Officer considered that there were no aggravating factors. The Judicial Officer took into account compelling mitigating factors including O'Brien's conduct prior to and at the hearing, his remorse, good character and clean disciplinary record, and reduced the suspension to a period of one week."
Pape has history with the Irish team having served a 10 week ban earlier in the year for kneeing Irish No8 Jamie Heaslip in the back, fracturing three vertebrae.
O'Brien's unavailability will stretch Irish playing resources even further as Rhys Ruddock arrived to replace the injured O'Mahony and lock Mike McCarthy has been called up to replace iconic skipper O'Connell.
O'Connell had as expected been ruled out earlier on Tuesday with a hamstring injury which has also brought down the curtain on his glittering 108-Test match career.
The Irish Rugby Football Union paid tribute to the 35-year-old O'Connell as "a leader, a warrior, and a gentleman" as they announced that he would undergo surgery this week.
As of yet no replacement has been called up for centre Jared Payne, who was ruled out of the tournament last Saturday with a foot injury.