Rugby preview: Word has filtered across the Irish Sea that Gloucester travel in expectation rather than hope. The premise is that they'll look to bully the Leinster pack and then unleash the wunderkinder of their three-quarter line.

It's a dog-eared script with which Leinster are familiar. Everyone looks to cut a swathe through their forwards, but few manage the task. There are one or two high-profile exceptions, notably in last year's European Cup semi-final defeat by Munster.

But they weren't manhandled by Toulouse, Bath or Bourgoin, all of whose forward units are highly regarded. It's a concentration thing with the Leinster eight. Scrum and lineout will have to improve to guarantee the platform the backs crave.

Will Green has been a pivotal member of this team and that he's playing injured again speaks volumes about him as a person and a player. Ronan McCormack is preferred at loosehead to Reggie Corrigan, with the latter set to equal the Leinster's most capped European Cup player record, held by his close friend Victor Costello (57 appearances), if he's sprung from the bench.

Cameron Jowitt will be given every opportunity to prove his fitness with Stephen Keogh a very capable deputy.

It'll be a massive occasion for Cillian Willis, if as expected, the 21-year-old starts at scrumhalf. Coach Michael Cheika still hasn't given up on Australian international Chris Whitaker, but the prognosis on the player's injured shoulder isn't good.

Willis has a good pass and is strong in defence, but the attribute he'll most require today is the confidence to trust his instincts. Good habits lead to good decisions under pressure; the right thing to do is exactly that irrespective of a game's profile.

Against the rush defence of the Borders in Leinster's most recent match, he needed to dummy the pass and make one or two breaks. It's about heads-up rugby, something this team can excel at.

Felipe Contepomi relishes the responsibility of playmaker, flanked by an outstanding three-quarter line and a fullback in the form of his career. When Leinster's back play is at its most fluent and devastating, there's no over-elaboration. It's about sharpness, timing, angles of running, peripheral vision and ruthless execution. The Leinster backs possess these traits as individuals, but when meshed into a team ethic, it's irresistible.

They are opposed as a unit by a Gloucester three-quarter line whose average age is 21½. The centres, Jack Adams and Anthony Allen, only turned 20 this month, while outhalf Ryan Lamb is barely older. All three, and 23-year-old wing Mark Foster, make their European Cup debuts.

Coach Dean Ryan's decision to plump for Lamb over the more orthodox attributes of Ludovic Mercier suggests a more expansive approach, but Gloucester won't ignore the more direct route. Italian international Carlos Nieto makes his first competitive start at prop, while in compatriot and captain Marco Bortolami and James Forrester, the pack possess seriously talented internationals.

Peter Richards is a lively, quick-thinking scrumhalf, while the mercurial Iain Balshaw and the abrasive Peter Buxton epitomise the diverse qualities of a Gloucester team, unbeaten in the English Premiership this season.

Having won the Challenge Cup final last season, Gloucester boast a certain European pedigree, but it's nowhere near as competitive as its elite sibling.

"I don't think there is any greater stage than Lansdowne Road in the European Cup and it will obviously be a huge test for this team," Ryan said. "In my opinion, they (Leinster) produced the performance of the tournament last year when they beat Toulouse away, and we obviously have a team with a low percentage of players who have been exposed to this competition."

Any team coached by Ryan will have an uncompromising pack, but this Gloucester team also have a cutting edge out wide.

The difference between the teams, assuming no advantage is eked out up front, is the match-up of the respective backlines: potential versus proven ability. Leinster need about 40 per cent of the ball to win this match and not alone make the 50th European Cup appearances of Malcolm O'Kelly and Girvan Dempsey memorable, but lay down a marker for the remainder of the tournament.

Leinster v Gloucester Lansdowne Road 5.30 On TV: Sky Sports 1

LEINSTER: G Dempsey; S Horgan, B O'Driscoll (capt), G D'Arcy, D Hickie; F Contepomi, C Whitaker/C Willis; R McCormack, B Blaney, W Green; T Hogan, M O'Kelly; C Jowitt/S Keogh, K Gleeson, J Heaslip. Replacements: H Vermaas, R Corrigan, O Finegan, S Keogh/A Byrnes, C Willis/A Dunne, K Lewis, L Fitzgerald.

GLOUCESTER: I Balshaw; J Bailey, J Adams, A Allen, M Foster; R Lamb, P Richards; C Califano, M Daves, C Nieto; M Bortolami (capt), A Eustace; P Buxton, A Hazell, J Forrester. Replacements: N Wood, O Azam, J Pendlebury, J Boer, R Lawson, L Mercier, R Keil.

Referee: C Berdos (France).

Previous meetings: None.

Verdict: Leinster to win.