The Leinster loosehead was sin-binned by referee Greg Garner after a video review in the first half of Ireland’s non-cap international clash at Thomond Park.

Ireland slumped to defeat in Limerick with Alex Cuthbert claiming two tries and Leinster full-back Zane Kirchner landing the Barbarians’ killer blow over many of his club-mates.

Craig Gilroy and the returning Chris Henry claimed scores for a scrappy Ireland outfit. Paddy Jackson’s late converted try handed Ireland a sniff of victory, but the BaaBaas held out.

Fly-half Ian Madigan escaped censure for stamping on Georgia lock Mikautadze when a maul collapsed in the 32nd minute, but McGrath was handed a yellow card for his actions at the same breakdown.

The 25-year-old front-rower could face further retrospective punishment, however, and any eventual sanction could threaten his World Cup participation.

France lock Pascal Pape was handed a 10-week ban for kneeing Ireland number eight Jamie Heaslip in the back during this year’s RBS 6 Nations.

Any suspension for McGrath would not start until Ireland’s World Cup warm-up games in August.

There is no suggestion McGrath’s actions equate to those of Pape, but a ban of four or more weeks would leave his World Cup participation in doubt.

Ireland boss Joe Schmidt showed his immediate feelings on the matter by choosing not to send McGrath back into the fray at the end of his 10-minute sin-bin.

While the BaaBaas entertained, Ireland were meant to be experimenting, blooding the young and untested and ushering experienced men requiring matches back towards full steam.

Uncapped centre Colm O’Shea, with just four Leinster appearances to his name, struggled but never folded, while flanker Henry impressed in his first international outing since November.

The Ulster openside scragged and scrapped at every breakdown, exhibiting all the tenacity that drove him into Ireland’s starting side before his mini-stroke in the autumn.

The 30-year-old even claimed a second-half try, and must surely have done enough in Limerick to convince head coach Schmidt he is ready for the World Cup.

The Barbarians launched into free-spirited custom from the off, Wales wing Cuthbert coasting home after Ireland debutant O’Shea drifted too far infield.

Ireland levelled the scores through Craig Gilroy’s smart finish, the Ulster wing cutting a tight line off a five-metre scrum.

Madigan’s conversion handed Schmidt’s men a two-point lead, but probe as they might, Ireland could not increase that advantage before the break.

McGrath’s yellow card stymied solid build-up at the death of the half, allowing the BaaBaas some respite, though the world-famous invitational outfit did suffer a sin-binning of their own.

Prop Roberto Tejerizo was given his short-term marching orders at the end of the half, for persistent scrum infringement.

The Barbarians reclaimed the lead after the turnaround, former All Blacks wizard Joe Rokocoko always to the fore with a flick here and a trick there.

Leinster’s Zane Kirchner outsmarted O’Shea before chipping the cover to slide home in style.

Jimmy Gopperth converted before slotting a penalty – with the crowd booing the pragmatism – to set the BaaBaas 15-7 to the good.

Ireland rallied through Henry’s driving-maul score, but even with Madigan’s conversion still trailed by a point.

The Barbarians fired another riposte, Cuthbert burrowing home with a good flanker impression for his second score of the night.

Ireland pulled a last-gasp try out of the hat thanks to replacement fly-half Paddy Jackson, and Madigan slotted the drop-goal conversion to allow the game to restart.

Ireland again trailed by one point, with the game sliding into its final minute as the Barbarians restarted the action.

The BaaBaas were able to run out the clock, however, and claim a victory as much morale-boosting for their part as galling for Ireland.