Iain Henderson is a doubt for Ireland's summer tour as the knee injury he picked up in Saturday's draw against Munster is set to keep him out for a spell.
The lock had to be helped from the pitch midway through the first half at Thomond Park and despite initial fears easing that Henderson had damaged his ACL, he is understood to have done significant damage.
The 26-year old will almost certainly miss Ulster's potential Champions Cup play-off against the Ospreys, while he is also likely to miss out when Ireland play Australia in a three-Test series next month, the opener on June 9.
Meanwhile, Wayne Barnes will referee next week's Champions Cup final between Leinster and Racing 92.
The experienced English official last refereed Europe's showpiece club game in 2010 and will be assisted by Dubliner JP Doyle, who referees out of England, and Tom Foley.
Racing are unlikely to kick up a fuss about Doyle's background after he refereed their semi-final win over Munster well.