Captain Rory Best must shake off a stomach bug to face Italy in Saturday's Six Nations encounter in Rome.
Hooker Best missed Ireland’s captain’s run at the Stadio Olimpico on Friday, remaining at the team hotel in a bid to beat his illness.
Munster's Niall Scannell would be in line to start should Best fail to recover, with Leinster's James Tracy a potential late call-up to the match squad if required.
Ireland may now have to hunt their first Six Nations victory of the campaign without their 101-cap skipper, with Ulster's Best in a clear race against time for full fitness.
Joe Schmidt’s men lost out 27-22 in Scotland last weekend and must win in Rome to kick-start their tournament.
Vice captain Jamie Heaslip would take the armband in Best's absence, but Ireland are clearly giving 34-year-old Best every chance of a recovery.
Ireland entered the Six Nations without 56-cap hooker Sean Cronin, the experienced Leinster man ruled out of the tournament with a hamstring problem.
That has opened the door for the uncapped Scannell to step up, and the 24-year-old from Munster remained an unused replacement in Scotland.
Leinster hooker Tracy made a try-scoring Test debut in Ireland’s 52-21 victory over Canada in Dublin in November.
The 25-year-old was initially overlooked for selection for Ireland’s Azzurri clash, but has been omitted from the Leinster squad to face Treviso in Italy on Sunday.
