Ireland have suffered a blow ahead of Saturday's visit of South Africa after hooker Rory Best pulled out of the squad with a calf injury.

Best's absence adds to an increasing injury list as props Cian Healy, Marty Moore and Nathan White have already been ruled out of the clash with the Springboks in Dublin.

"Following a medical review on Tuesday evening Rory has been ruled out of selection for the game against South Africa," an IRFU statement read.

"His calf strain that has been slower to heal than expected. He is partaking in modified training but a decision has been made not to risk him this weekend and his progress will continue to be monitored."

Sean Cronin is expected to replace the Ulster forward at number two.