The key battle
Seilala Mapusua v
A host of intriguing one-on-ones to choose from -- Doug Howlett v Sailosi Tagicakibau and Donncha O'Callaghan v Bob Casey are two that jump out -- but the clash of the two wrecking-ball No 12s is the show-stopper.
Mapusua has the edge in terms size (5ft 11ins, 16st versus 5ft 9ins, 14st), but that will not matter to Tuitupou, who will relish the chance to take down the big Samoan.
The two know each other well from New Zealand and the Premiership and their collisions should be seismic -- they may even veer into yellow-card territory.
Match betting: London Irish 6/8, Munster 7/5, draw 20/1
Form guide: London Irish WWWLW Munster LWWWW
Stat: In the 15 years of Heineken Cup competition, Munster have played an English side away on their opening match six times, winning only once -- against Leicester Tigers at Welford Road in 2006.