European Cup/Leinster v Gloucester: "Fail to prepare, prepare to fail." Roy Keane's motto has a certain resonance for any sportsperson. It's a maxim that 21-year-old Cillian Willis seems to have adopted and one that should stand him in good stead.

The former Blackrock College schoolboy and UCD student will make the Leinster match squad for Saturday's Heineken European Cup clash with Gloucester at Lansdowne Road: the question is whether he'll start or be named on the bench.

At the moment Leinster coach Michael Cheika is monitoring the fitness of former Australian international Chris Whitaker, who suffered a trapped nerve in a shoulder during the Magners Celtic League game against Connacht. The former Waratah player had to retire early and hasn't played since missing the victory over Munster and the defeat by Borders.

The problem is a power issue in the shoulder and while he returned to the training pitch earlier this week, he's rated no better than 50/50 to rehabilitate in time for Leinster's pivotal match against the English West Country club. If he fails a fitness test then Willis will start.

It'll be a tough European baptism for the former underage international in his first year on a development contract with the province, but few will doubt his aptitude. The Leinster Academy manager, Colin McEntee, has monitored and nurtured Willis's progress over the past two seasons.

"He's a very dedicated young fella with a very good pass - crisp and accurate. Defensively he's strong and physical, particularly around the fringes of rucks and mauls. At times he's too brave for his own good and he's earned the nickname 'Scrappy' because he won't take a backward step.

"He's got an eye for a gap too, possesses a very good all-round game. He got his first competitive run-out for the senior side this season last Friday and did well, especially as it was his first competitive outing for four or five months. He works incredibly hard at this game, always has done, and that would be far and away above what we would have asked him to do at the academy. He's been unlucky with injuries."

The latter is a reference largely to last season, in which Willis picked up three hamstring injuries in succession, limiting his appearances at provincial level to a few A matches. Having worked assiduously on rehabilitation, he then incurred shin splints during the summer.

There's no doubting his pedigree quite apart from the fact that he's Brian O'Driscoll's cousin; the boys' mothers are sisters. Living in Greystones he was educated at Blackrock College, where he won a Junior Cup medal and endured the disappointment of losing a Senior Cup final. During that time he played for the Leinster Schools.

Further representative honours followed in the 2003-2004 season, when he played for Leinster and Ireland at under-19 level and also made his senior debut for the province, lining out in a couple of friendly matches against Coventry, and lending a certain symmetry to Saturday and Gloucester.

In the 2004-2005 season he was Leinster's and Ireland's scrumhalf at under-21 level and played a number of A games at provincial level, matches of that ilk a brief respite the following season when he was largely injured.

He now finds himself on the cusp of a European debut because of the broken jaw sustained by Guy Easterby in last week's game against the Border Reivers. The latter's departure after 19 minutes meant Willis was given a little over an hour directing the Leinster pack.

If Whitaker does miss out then Leinster must turn not alone to one tyro at this level in the number nine shirt but also to a player with even less experience at scrumhalf in flanker Niall Ronan.

Last season coach Cheika asked Ronan to work hard on his passing skills so that he could deputise at scrumhalf in pressing circumstances.

That prescience could be vindicated at the weekend. The three scrumhalves Leinster registered for the European Cup were Easterby, Whitaker and Willis. Matthew D'Arcy, who sat on the bench against Munster, is ineligible - there is a wild-card slot available but Leinster won't want to use it this early in the campaign - thereby thrusting forward Ronan's candidature.

The former Meath Gaelic footballer is a very skilful player but a European Cup tie is not the occasion to road test those acquired attributes. For Willis, it's a simple numbers game: nine or 16.