Sean O'Brien and Jared Payne are in doubt for Ireland's final autumn Test against Australia in Dublin on Saturday.
Ireland have drafted in Munster flanker Peter O'Mahony to cover O'Brien and already had Rory Scannell on hand to cover centre Payne.
Ireland's assistant coach Andy Farrell has insisted both men had merely carried "lower-limb tweaks", and so sat out Friday's captain's run training session.
Farrell remains confident the influential duo will be fit for Saturday's Test, but Ireland will check on both men on the morning of the match.
"We've had a couple of guys that's had a couple of niggles, and the captain's run is normally just a stretching-legs type session," said Farrell.
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"We made a couple of decisions this morning to rest Jared Payne and Sean O'Brien and see how they are in the morning.
"We'll have a discussion in the morning about their situation.
"They both have just lower-limb tweaks, that's what normally happens during the week.
"You pick things up on the way from the game, through the week and so on.
"The main session was yesterday and we decided to give a couple of players more time.
"We've kept Peter O'Mahony here, and we've got Rory Scannell as well covering for Jared Payne.
"All the main work's been done already, that's why we are resting them, to give them every chance to feel 100 per cent."
