CIYMS marched into the semi-finals of the Irish Senior Cup after skittling 2009 winners Leinster for just 61 at Rathmines.
James Cameron-Dow struck two early blows as he removed Ireland's newest cap Gareth Delany and makeshift opener Bilal Azhar.
It went from bad to worse as Allen Coulter struck two massive blows as overseas player Monil Patel and George Dockrell went for single figures too, leaving the hosts innings in tatters at 18 for 4.
There was a recovery of sorts as top scorer Hugh MacDonnell (19) and Chris Janik added 25 before the introduction of Obus Pienaar and Jacob Mulder brought the innings to a swift conclusion.
Pienaar claimed 4 for 11, accounting for Janik, Saqib Bahadhur,Hardus Venter and Tristan de Beer.
Inbetween, Mulder dismissed MacDonnell and Danny Coad with Leinster's last six wickets adding just 18 - 61 all out in 23.3 overs.
Bilal Azhar (3-43) struck the stumps three times to account for Chris Dougherty, Nigel Jones and John Matchett but it was in truth only about earning respectability.
Obus Piennar hit 18 before being the last wicket to fall - trapped lbw by George Dockrell, as Jason van der Merwe (12*) saw CIYMS to the six-wicket win in the 14th over.
The win ensures two teams from the NCU and Leinster will contest the semi-finals on August 4th.
CIYMS join Pembroke and Phoenix in the last four, but Waringstown and Instonians will have to try again next week after their game today was abandoned with the Shaw's Bridge side on 58 for 2.
Cricket Ireland have yet to confirm when the semi-final draw will be held.
In the National Cup quarter-final Derriaghy emerged victorious in a sudden death bowl-out with Midleton.
The Belfast side had been dismissed for just 99 and looked to heading out before what the club dubbed 'The Miracle of Midleton' happened. Not so much of a miracle but more of a regular occurrence in Cork as the rain fell and the game was abandoned, resulting in cricket's equivalent of the penalty shoot-out.
The long journey back home would have been less taxing after they held their nerve to strike twice in sudden death to win 2-1.
They now face Railway Union in the semi-final on August 4th.
Meanwhile, in the Ulster Plate semi-final, Fox Lodge knocked out holders Donemana 2-1 in a bowl-out at The Holm.
Lee Finlay and Jamie McIntyre struck for the Foxies, while Dean Mehaffey hit for the home side.
Fox Lodge will now play either Eglinton or Bonds Glen who meet next Sunday.
IRISH SENIOR CUP SCORECARDS