THE Indian rope trick is said to be the toughest trick of all to pull off, but the five teams who have scaled the Magners League summit might beg to differ.

For the Scarlets, Ospreys, Ulster, Leinster and Munster, the challenge too far has involved successfully defending a league title.

Indeed, at times, Celtic rugby's champion sides have come closer to mirroring Tommy Cooper's take on the illusion from the sub-continent.

Sporting his fez, Tom used to hurl a rope in the air and watch it come crashing to the ground before declaring: ''Indian rope trick,'' with the suspicion being that he had never truly travelled out east to learn the secrets of the ultimate feat of conjuring, involving as it does illusion, suspense and disappearing magicians and their assistants.

All that has vanished for Celtic rugby's crown wearers since 2003 has been their ability to stay at the top of the pile the following season, with no side managing to complete back-to-back titles.

Sean Holley spoke well at the Ospreys' press conference this week about success being a drug and how everyone at the region couldn't get enough of it.

But as defending champions, the Liberty Stadium team have had cold-turkey seasons.

In 2005-06 they finished seventh and two years' later they ended up in the same down-table spot after winning just six league games.

Such impressive grand-final winners in May, they will look to improve this time, but the challenges for a champion side are obvious.

They face having to motivate themselves afresh after conquering all in the previous campaign, while other teams will lift their performances against them.

''To retain a title,'' said Jose Mourinho during his time at Chelsea football club, ''you have to be better than when you won it first.

''That's easy to say but difficult to do.''

Can the Ospreys be better than they were last term? There are no guarantees, not with Filo Tiatia having packed away his boots, the big man's crushing presence as an impact player certain to be missed.

They are also likely to be hit harder than ever by international calls, offering hope to those rivals who provide fewer players to national causes — which means pretty much everyone else in the league.

But there are also reasons for Ospreys supporters to be hopeful, not least because the squad that finished last season like a train is still largely together.

They will effectively have two new players in fit-again Ian Evans and Duncan Jones, while Richard Fussell and Mefin Davies promise to be useful recruits and youngsters such as Dan Biggar, Ryan Bevington, Tom Prydie, Gareth Owen, Craig Mitchell, Ashley Beck and Justin Tipuric will continue to develop.

Biggar is still only 20, yet already has six Wales caps. And especially encouraging for the Ospreys and the national team is that he is a work in progress, a player who will improve immeasurably as the seasons go by.

But make no mistake: the 2009-10 champions will be unable to rely too much on their glitter band of internationals, not with seven Magners League games to be played during the autumn Test period and the Six Nations.

It wouldn't hurt the Ospreys, either, if their legal team did their bit at the region's appeal next Tuesday against a four-point deduction and a £100,000 fine for postponing the game against Ulster last March.

Spat

What the Italian newcomers to the tournament must think of the spat between the champions and the league hierarchy is anyone's guess.

Perhaps Rowland Phillips will help translate how things are done in this part of the world, assuming Aironi's new defence coach is on his way to mastering the language.

Before he headed for northern Italy one of the game's great characters quipped: ''I have a language disc in the house that says I will be speaking Italian by the end of it. I listened to it once and, well, let's say it didn't do what it said on the tin.''

The introduction of Aironi and Treviso will add to the league's unique selling point, namely its variety. And, presumably, it will not harm the coffers of Celtic rugby, either.

Inauspiciously, but predictably, the fixture schedulers have missed a beat on the opening weekend.

They could have matched the Ospreys against the Scarlets and paired the Blues against the Dragons, to launch the season with a bang, perhaps selling the two derbies as a Millennium Stadium double header: D-Day.

Dream on. The Scarlets will host the Ospreys at ten-past eight on a Saturday night in October. And the schedule before Christmas shows only one Saturday afternoon encounter for the regions, Scarlets v Connacht on September 11.

One day, someone will think of supporters. Probably around the time a weather bulletin comes in telling us that hell has frozen over.

Who are the main threats to the Ospreys' ascendancy? Munster, for one, with Sam Tuitupou heading a list of recruits that includes South African prop Wian Du Preez.

The other main Irish provinces, Leinster and Ulster, will also challenge hard, along with the Blues, who have been surprisingly bullish for a side whose league achievements over seven years hit a peak last term with their capture of the Specsavers Fair Play Award.

But they do look in decent shape, with Dan Parks likely to give them control and their other headline signing of the summer, Kiwi forward Michael Paterson, another useful acquisition.

Are Dai Young's forwards too old? Well, with Maama Molitka, 36, Martyn Williams, 35, Xavier Rush, 33, Tau Filise, 33, and Paul Tito, Gary Powell, Gareth Williams, Deiniol Jones all children of the 70s as well, there is no danger of the Blues eight being confused with a Scout troop.

The Scarlets have done an impressive selling job this summer, somehow managing to set a season-ticket record despite finishing with only Connacht below them last term.

But the challenge is to back up the good marketing with performances on the field.

The Llanelli-based side, with Regan King and Morgan Stoddart fit and Stephen Jones and David Lyons still around to offer experience, will be determined to have a much better campaign.

Improved

But they haven't radically improved the squad that lacked depth in 2009-10. They have promising youngsters but need them to come of age quickly.

Wales are unlikely to place too many demands on them, which will be a big plus for their prospects.

But, all things considered, if they finish in the top half of the table they will have done well.

The Dragons were feted for their efforts last term, being named team of the season in Wales, despite finishing seventh in the league. And Paul Turner was named Magners coach of the year.

Imagine the fuss if they did what Ulster, another unfashionable outfit, did in 2006, and actually lifted the title.

Expect Wales and Ireland to dominate, with the silverware likely to be claimed by one of four sides – the Ospreys, Blues, Munster or Leinster, as long as their front row holds up.

Those who enjoy variety would cheer a Blues' success.

But there is something to be said for enduring quality.

The Magners League is overdue a champions' encore. For the Ospreys, the challenge is clear.