Ireland captain Rory Best didn't train with his team-mates on Tuesday but is still expected to be fit for Saturday's clash with Scotland in Dublin.
Ireland team management revealed that the hooker had a tight calf but expect him to return to training by Thursday.
"The medics feel like he should be fine and ready to go for Thursday," Ireland's skill coach Richie Murphy told the BBC.
"He was a little tight in the calf at the end of training yesterday."
Murphy said the 33-year-old's absence from training was a precautionary measure, although Best must prove his fitness on Thursday when Ireland announce their team for the Scotland match.
Eoin Reddan and Cian Healy, who missed Ireland's 58-15 win over Italy on Saturday, resumed training this week and are available for selection.
Scrum-half Reddan missed the Italy clash with a calf injury and prop Healy pulled out with a hamstring problem.
"Eoin Reddan returned to training on Tuesday. Cian Healy trained Monday and Tuesday as well," added Murphy.