While the senior team beat Constitution to put them in pole position in AIB League Division 1A, the Under-21s enjoyed an 18-5 victory over the Leesiders to qualify for the semi-finals of the Frazer McMullen Trophy.
Their reward is a home tie against a Lansdowne Under-21 side that beat defending champions UL Bohemians, winning 12-9 after extra-time.
UL have won the title for the last two seasons, so there wil be a new name on the trophy this year.
With the Lansdowne senior team unbeaten all season in the AIB League, the U-21s will be hoping to add to the club's All-Ireland success.
The other semi-final will be an all-Munster affair between Shannon and UCC. Shannon overcame their Terenure College counterparts 20-18, while UCC enjoyed a one-point win over UCD, running out 15-14 winners.
2009/10 FRAZER MCMULLEN TROPHY -
St, Mary's College 18 Cork Constitution 5, Templeville Road
UCD 14 UCC 15, Belfield
UL Bohemians 9 Lansdowne 12, Annacotty
Shannon 20 Terenure College 18, Coonagh
Saturday, April 3 -
St. Mary's College v Lansdowne, Templeville Road
Shannon v UCC, Coonagh
The final will be played on Saturday, April 10, with the venue to be decided following the semi-finals.