Munster lock Paul O'Connell could miss the rest of the season after suffering ankle ligament damage in Saturday's Magners League win over Leinster.
O'Connell was withdrawn in the second half after landing badly from a line-out.
The full extent of the injury is not yet clear and it will be reassessed after 10 days.
Munster face Brive away in the Amlin Challenge Cup quarter-finals on Saturday, a game O'Connell will miss.
Mick O'Driscoll is likely to deputise in the second row.
It had been feared that O'Connell had snapped his Achilles tendon against old rivals Leinster.