It is difficult to see where holders Belvedere can make game-breaking inroads into a rangy, skilful Blackrock side at Donnybrook this afternoon.

Blackrock have already swept past St Michael's (47-7) and CBC Monkstown (43-6). They are unhindered by injury as coach Frank Macken has the comfort of selecting the same starting 15 that nailed St Michael's in the quarter-final with one change to the bench where back rower Mark Rooney comes in for Connacht interpro David Heffernan.

Their vigour up-front is a sight to behold from the imposing shape of props Denis Buckley and Arthur Lyons, both keen to and capable of offloading in minimum space, all the way back to the knife-through-butter running of full-back Andrew Conway.

For their part, Belvedere do offer the kind of physical impact in the contact area that Rock have not had to contend with so far. They will not have things all their own way.

Centre Niall Myron could make a stunning comeback from a severe cruciate knee injury in October to make a contribution, probably from the bench. Wing Richie Sheridan (ankle) and reserve prop Paul Gilsenan (knee) will need to prove their fitness to be considered.

There is plenty of grit from front rowers Cathal O'Flynn, Dylan Casey and Chris O'Brien, flankers Adrian D'Arcy and Michael Oyuga, and number eight Ben Geraghty. They are allied to an able back division in which crafty scrum-half Hugo Nolan, centre Colly O'Shea and full-back Ben Woods are the boys most likely to cause damage.

Terenure have been frustratingly inconsistent in their two previous encounters sending out a chilling warning in the form of an opening-day 43-5 drubbing of an admittedly sub-standard Castleknock, only to follow it with a dreary 9-5 eclipse of Clongowes Wood in the quarter-final.

Okay, it is one of Clongowes' great traits that they concede nothing easily, but the number of basic errors and the absence of creativity made Nure unrecognisable from round one. They will again go with the same side against St Mary's at Donnybrook on Tuesday.

Centre Maurice Walsh and wing Neil Flynn should be back to strengthen a St Mary's side that has made it this far by flying beneath the radar. They will look to a solid front row, locks Liam Curran and captain Ronan Lennon, as well as number eight Mark Fallon to stem the flow of pressure.

Meanwhile, down south, Pres Cork will wait anxiously for news on the shoulder injury of their Munster (under-18) Schools openside Conal Murphy. He will need all the time he has to make it back for the city derby against Christians. James O'Sullivan is the likely replacement, if required, at Musgrave Park on Wednesday.

CBC are in good shape, recovering from an opening day disappointment to St Munchin's (14-5) to knock off holders Castletroy 17-3 in the quarter-final. Munster under-20 lock Brian Hayes is their go-to man.

Rockwell will look to their colossal number eight Patrick Butler to lead by example in what is sure to be a wincingly physical encounter with St Munchin's at Clanwilliam on Thursday.

The Limerick boys cracked CBC and Ard Scoil Rís (33-8) to move into the driver's seat as one of only two unbeaten sides – the other being Pres – left in the competition. Backs Craig O'Hanlon and Robert Guerin and number eight Ger Burke are their stalwarts.

In Ulster, Methodist got one hell of a fright from Cup specialists Campbell (21-14) in the quarter-final last Saturday before emerging with their ambition intact. It may well have been the best thing that could have happened.

They should be free from any threat of complacency at Ravenhill on Wednesday as they tackle a determined Ballyclare High, who already executed an unlikely comeback in their defeat of the seeded BRA (15-13).

The various bumps and bruises should have healed by tomorrow in what will, most likely, be the same RBAI fifteen that got them through to the semi-final.

Institution have been transformed by the move of their best back Paddy Irwin to full-back where he has licence to come into the line.

They will be favoured to account for last year's finalists Regent House, who carried too much weaponry for Larne Grammar (21-5) in the quarter-final, at Ravenhill tomorrow.

Sligo Grammar will be able to call on five of the Garbally Junior Cup-winning side of 2006 as the schools meet in the Connacht Senior Cup semi-final at Ballinasloe tomorrow, as champions Coláiste Iognaid await the winners.

When Garbally closed down the boarding wing of the school, the side was split into pieces. The Grammar was the main beneficiary. Scott Oates, David Butler, Tom Callanan, Eamon Gorman and Pat Hughes are all likely to cross swords with their former teammates.

Fixtures

LEINSTER SENIOR CUP SEMI-FINALS

Today Belvedere v Blackrock, Donnybrook 3.00 Tuesday St Mary's v Terenure, Donnybrook 4.15

MUNSTER SENIOR CUP SEMI-FINALS

Wednesday CBC Cork, v PBC Cork, Musgrave Park 3.00 Thursday Rockwell v St Munchin's, Clanwilliam 3.00

ULSTER SENIOR CUP SEMI-FINALS

Tomorrow RBAI v Regent House, Ravenhill 3.00 Wednesday Methodist v Ballyclare High 3.00

CONNACHT SENIOR CUP SEMI-FINAL

Tomorrow Garbally v Sligo Grammar, Ballinasloe, 1.30