THIS season's European Cup represents a vastly different and more demanding challenge than last season. The four Irish provinces face extremely tough assignments tonight.

The Irish provincial champions, Munster, meet a Cardiff side that includes 15 Welsh internationals at the Arms Park and while that encounter is being fought out Leinster and Ulster will be engaged on home soil against two club sides who would give any international team an examination, and would be favoured to beat most, Leicester and Harlequins respectively.

Connacht, like Munster, will encounter Welsh opposition - Dunvant - in the European Conference on the Welsh club's ground at Broadacre just outside Swansea.

Both Leinster and Munster had to wait until last night before finalising their teams because of injuries. Munster's problems were with full back Dominic Crotty, scrum half Stephen McIvor and prop Paul McCarthy but all were passed fit. But, in fact, Munster have made two changes from the side that beat Milan, both at prop forward. Ian Murray comes in at loose head for John Fitzgerald and Noel Healy at tight head for McCarthy. Those alterations are made bearing in mind that Munster meet Wasps next Saturday.

Leinster will be without wing Denis Hickie and back row Dean Oswald. Paddy Gavin and Darragh O'Mahony retain the wing berths and Stephen Rooney will again be on the open side flank.

Leinster, however, make two changes from the side that lost to Llanelli. Alan McGowan returns at outside half in place of Richard Governey and Martin Ridge, fit again after a shoulder injury. takes over from Ray McIlreavy in the centre.

Ulster, who named their side on Monday night and already without centres Mark McCall and Maurice Field, will decide today if Sheldon Coulter will be fit to play in the centre. He sustained a knock in the face against Caledonia last Sunday. The expectation is he will be fit. Likewise second row Jeremy Davidson, who is under treatment for a toe injury.

Played four and won three represented a satisfactory return for the provinces last weekend with wins by Ulster and Munster in the Cup and Connacht in the Conference. Ironically the Irish side that did best of all last season in the Cup, Leinster, were the only losers and that defeat by Llanelli has severely damaged their prospects of emulating last season's achievement when they reached the semi-final.

Munster go to Cardiff on the back of that 23-5 win over Milan. But Cardiff, who lost in the final last year after extra time to Toulouse, represent a very difficult task. Cardiff make just one alteration from the team that lined out against and beat Wasps last Sunday. Mark Bennett comes in on the flank for Jamie Ringer. Bennett, in fact, replaced Ringer during the win at Loftus Road.

Munster will be very conscious that last season Cardiff did a demolition job on Ulster winning in Cardiff by 46-6.

"We are going there in a very positive frame of mind. We are aware of their strengths, but it is not our intention to go out with containment on our minds," said Munster manager, Colm Tucker.

The Cardiff back line, marshalled by half backs Robert Howley and Jonathan Davies, is a very powerful unit and Munster's defence will need to be tight. They must be vigilant, too, against Howley's breaks. He is Cardiff's leading try scorer this season.

The line out ability of John Wakeford and Derwyn Jones caused Ulster major problems last season and indeed also did damage to Leinster in the semi-final. Mick Galwey and Gabriel Fulcher have the task of matching that pair.

Cardiff made a very poor start to the season losing their first three league matches and they have proved vulnerable to sides that attack them as evidenced by the concession this season of no fewer than 29 tries.

Leinster must win tonight against Leicester to keep their interest alive in the competition. Leicester will be without number eight Dean Richards and left wing Rory Underwood, but still have a very accomplished side and a front row rated the best in the English league. They also have a line out ball winner in second row Martin Johnson and former Leinster player Ireland A international Eric Miller is at number eight.

Leinster's fade-out in the second half against Llanelli was as remarkable as it was unfortunate and a similar happening tonight will be punished equally severely. Leinster must match the Leicester tight five, and they have enough experience to do it. Neil Francis, Malcolm O'Kelly and Victor Costello will need to assert themselves in the line out and Leinster must also protect their possession.

Harlequins have swept aside all opposition this season and no area has been more devastating than their tight five, an all international quintet of Irish, English, Welsh and French internationals. No one in it has prospered to greater effect than Ireland international hooker Keith Wood. Ulster manager Ken Reid got it right when he said last night: "We must not allow their tight five to dominate us, if we do then we will be in trouble."

So a very big task for the Ulster tight forwards, Richard Mackey, Stephen Ritchie, Gary Leslie, Paddy Johns and Jeremy Davidson. Johns, Davidson and number eight Steve McKinty carry Ulster's line out hopes against the Llewellyn brothers Glyn and Gary and Harlequins six feet six inches number eight Mike Watson.

Ulster must seek to close down the space and tackle around the fringes. Harlequins will exploit space and in Will Carling at outside half they have a man who has been impressive in that role. Outside him are two rugby league centres Gary Connolly and Robbie Paul and right wing Darren O'Leary is a tremendous finisher. Former Ireland full back Jim Staples has also been scoring tries regularly. He may be tested tonight with the high ball by Ulster outside half David Humphreys.

A bit of wind and rain and Ulster passion would not go amiss tonight and Ulster do have a very good record at Ravenhill. But Harlequins, with their multi national outfit, go into the match as overwhelming favourites.

Connacht will go to Dunvant with more than tenuous hope of building on their very good win last week against Padova. Dunvant won promotion to the first division of the Welsh League last season and have performed well in the top grade, beating Swansea and Neath. They are especially formidable on home soil. But they lost at Orrell in their opening Conference match last Saturday by 32-29. That was a very disappointing result. They have as a consequence made six changes in the side three in the backs and three up front.

Connacht have a match winner at outside half in Eric Elwood and very hard working, energetic and abrasive pack well moulded by coach Warren Gatland. If they give Elwood the means, his experience and place kicking ability could steer Connacht to what would be a notable victory.