RUGBY SEÁN O'BRIEN INTERVIEW:THE PHRASE "tipping point" has been recently usurped by politicians and economists who could not tell us that there was a crisis until we were mired in financial gloom. Shane Jennings has this week reached a tipping point with his chances of lining out against Castres on Saturday less likely than it was at this time last week. Unlike the now discredited "Masters of the Universe", Michael Cheika has a plan.

On Tuesday, Jennings didn't train and Cheika was no happier about him turning out against the French side than 50-50. Yesterday the Leinster squad took a day off and with each passing hour the likelihood of Jennings withdrawing and Seán O'Brien stepping in for his first Heineken Cup start grows significantly. O'Brien is the plan.

While a player of Jennings' stature would be missed on any side - and no doubt Leinster are thinking of Castres away rather than rushing him for Castres at home - few who watched Leinster's freezing point win over Dragons last Saturday at the RDS will entertain anything other than hopeful thoughts about the Tullow influence at openside flanker.

O'Brien has shown flashes before and from what people saw, those glimpses were heartening. Then when he galloped through last week, changed direction and dismissively handed off the Dragons outhalf to score Leinster's first try, the ranks of the converted grew considerably.

"I keep doing extras and try and make myself better on the field, so while it makes life difficult for me, with the competition there fierce, it's good for me as well," says the 21-year-old, who won man of the match for his performance.

"I'm fairly happy with the amount of games I've got so far this season. I started against Ospreys and Connacht and then came on in another three in the Magners league. I wasn't in the Heineken Cup squad because I was injured for both (Wasps and Edinburgh)."

Before this year few had heard of O'Brien, who was then busily engaged in both playing in the Leinster Academy and coaching his local side Tullow, who reached the finals of the Towns Cup last season before they were beaten by Navan 33-16. This season his natural force has made him an occasional, but also an eye-catching part of the Leinster squad.

"It (coaching Tullow) keeps my feet firmly on the ground when I go back home and it's good to get an insight into a bit of coaching," he says, explaining the merits of mucking in with the people who knew him before he ever put a blue shirt over his head. "And it gives me a better outlook about what my coach wants from me when I'm up here."

This season the Leinster performances have been flecked with his bullocking and competitively charged contributions. A low slung, rough diamond, who likes to put his hand on the ball and do damage around the park, O'Brien has been waiting for the chance.

"It's very hard at the minute," he adds. "With the quality of the backrow that's there - Jamie (Heaslip), Jenno (Jennings), Rocky Elsom, Stephen Keogh. They are all top players. It's very difficult for me to get in there. I'm learning from them every week and every week I'm trying to learn the tricks of the trade. That's what I have to do, be a smarter player when I'm out there."

The current sporting paradigm among young professional players is that they can achieve anything if they keep working hard and pick up on their luck. They all have to believe that their time will come and they speak in terms of "doors opening" and "consistent performances". Every match is a trial. "Every match I play I want to go out and prove that I'm good enough to play Heineken Cup, play every game for Leinster," he explains. "I spoke to Michael (Cheika) and told him that I wanted to be playing more regularly on the first team. He's given me my chance this season, so every chance I get I'll have to do the job.

"He (Cheika) didn't really say much to me, said that it was a realistic goal. Obviously you want to be playing every week, in the starting 15. No matter who is there in the backrow, if I'm playing well and being consistent in my performances, he has to give me a run."

Sooner rather than later it seems.