Leinster, a team so long defined by failure, are odds-on favourites to beat Ospreys in the RaboDirect PRO12 Grand Final at their Royal Dublin Showground home tomorrow, a result that would clinch an unprecedented Celtic/European double and cement their reputation as the greatest club side of the modern era.

The Irish outfit completed the first part of that double when they hammered Ulster 42-14 in the Heineken Cup final at Twickenham a week ago. No side has been able to clinch both European and domestic titles since Wasps in 2004, but Leinster have an unrivalled depth of talent and have lost just one match since last September.

Small wonder that the bookmakers are offering odds as stingy as 1/4 for a Leinster win. However, Joe Schmidt, the Dubliners' head coach, made it clear straight after last weekend's win that neither he nor his players would be taking tomorrow's opponents lightly.And with good reason.

The one side that did manage to interrupt Leinster's long-running streak this season was Ospreys, who pulled off a shock 23-22 victory in Dublin on March 23. Granted, Leinster were easing off by that late stage of the season, already virtually assured of their place in the PRO12 play-offs, but defeat was a timely reminder of the dangers that the Swansea-based Ospreys can pose.

For Leinster fans, the result also brought back bad memories of the inaugural PRO12 Grand Final, in 2010, when Ospreys shook off their underdogs' tag with a 17-12 win at the RDS. Leinster were accused of complacency that day, a charge revived last year when they again fell at the final hurdle, going down 19-9 to Munster at Thomond Park just seven days after their epic Heineken Cup victory over Northampton Saints.

Schmidt, though, is not just talking the talk about taking tomorrow's final seriously, for he has chosen a team with 13 full Ireland internationals to take on the Welsh side. The two players who have not worn the shamrock are winger Isa Nacewa and prop Heinke van der Merwe, who have represented Fiji and South Africa respectively.

The Ospreys side bristles with Test players as well, and they should have the measure of Leinster in the forward exchanges. On top of which, they have a certain track record when it comes to overturning the odds, most recently demonstrated in their astonishing 45-10 thrashing of Munster in the PRO12 semi-final.

Ospreys may lack a little quality behind the scrum, in comparison with Leinster at least, but fly-half Dan Biggar, man of the match in the 2010 final, has made a dramatic return to top form in recent weeks. On top of which, they have Shane Williams on the wing, looking to end his stellar career on a high.

"Leinster are a great team," said Steve Tandy, the Ospreys coach. "What they've achieved in Europe over the last four years speaks for itself, and the nature of their win against Ulster last weekend means that they'll be full of confidence. Playing at home in front of their own fans is another bonus for them and will make the task even more difficult for us.

"We will obviously do our homework and analysis on them, but the key thing for us is about our own performance. If we focus on our own game and the areas that we can control, then we'll be able to compete and we'll be in the game.

"It's going to be a great day, there's a big Osprey support travelling out to back the cause and we want to put on the kind of performance that will make them proud of their team."

Meanwhile, Leicester and Harlequins will do battle for the Aviva Premiership crown before an 83,000 capacity crowd at Twickenham this afternoon. Harlequins finished top of the table at the end of the regular season, but fast-improving Leicester are favourites to win what will be their eighth consecutive Premiership final.