Shane Jennings accepts 'the whole of Ireland' will probably rank Leinster as underdogs in tomorrow's Heineken Cup semi-final showdown against holders Munster.

Leinster have never previously reached a Heineken final, falling three times at the tournament's penultimate stage.

Munster, meanwhile, are chasing a third European title in four seasons, and their 43-9 quarter-final demolition of the Ospreys suggests they could make it mission accomplished.

When the fierce Irish rivals last met in Europe, Munster romped home 30-6 at Lansdowne Road.

And many pundits feel tomorrow's sold-out Croke Park encounter in Dublin could follow a similar pattern.

'To be honest, it is hard to say whether it is a benefit or a hindrance knowing each other so well,' said flanker Jennings.

'But we have played them twice this season and they won on both occasions, so they have to go into the semi-final as hot favourites.

'Each team pretty much knows what to expect from the other, but the whole of Ireland will quite rightly regard us as the underdogs. We have a massive task ahead of us in taking on the champions of Europe, and playing in Dublin is no great advantage to us either.

'The majority of the Munster boys know Croke Park well and have been successful there, so it is of no additional benefit for us.'

Perhaps the most anxious observer tomorrow will be Lions head coach Ian McGeechan.

Up to 10 of the players selected for the South Africa tour that starts later this month could feature at Croke Park, and McGeechan has already been struck by an injury blow, losing Munster scrum-half Tomas O'Leary from his plans.