Lions prop Cian Healy could be a fitness concern for Ireland's autumn internationals after picking up a hamstring injury in training.
His club Leinster said he faced a "significant layoff" and so he may face a battle to be fit to face the Springboks on 8 November.
More immediately, the prop will miss Leinster's Pro12 game against Cardiff Blues on Friday.
Healy, 26, may also be a doubt for next month's European Champions Cup games.
Leinster open their European campaign with a home game against Wasps on 19 October before taking on Castres away seven days later.
After facing South Africa on 8 November, Ireland take on Georgia and Australia over the following two weekends.
Healy has earned 47 caps since making his debut for Ireland in 2009.
If he is ruled out for Ireland, his Leinster colleague Jack McGrath would be the obvious choice to start at loose-head against the Springboks.
Munster lock Donnacha Ryan has already been ruled out of Ireland's autumn games because he requires toe surgery.