Rugby:Ulster captain Johann Muller is expected to be out for at least eight weeks after fracturing a bone in his arm in the province's 25-6 Heineken Cup victory over Northampton at Franklin's Gardens on Friday night.

It continues a miserable run of injuries for the South African lock, who only returned to action last weekend in the Pro12 game away to the Scarlets after missing five weeks with a thumb injury.

Muller went off after 50 minutes of the game against the Saints and was replaced by Nick Williams as Ulster brought their unbeaten run to 13 games this season.

A statement from Ulster Rugby confirmed that an X-ray on Saturday morning showed that Muller suffered an undisplaced fracture of his radius that will keep him out for at least eight weeks.