Saints, who have been struggling in recent weeks, found a new lease of life, and inspired by American Dee Proby, they led 42-38 at the break.
The second half was tense but credit to the Saints, they found key baskets coming down the stretch, much to the delight of coach Joey Boylan.
Boylan said: “ I have never lost faith in this group and I think we showed true grit to defeat the champions on their home court.
“Our defence in the second and third quarters laid the foundations for our win but no silverware was handed out and now we must build on this performance.”
UCC Demons travelled to play Kubs and came away with an impressive 101-47 win.
Demons will now have a home quarter-final against Garveys Tralee Warriors that is sure to attract a capacity attendance to the Mardyke Arena on December 1.
Templeogue hosted Belfast Star and had to work hard before securing a 90-81 win.
The Dublin side led 46-41 at the break but a 30-point contribution from Lorcan Murphy ensured his side a quarter-final berth.
Moycullen came out on top in the Galway derby over Maree, winning 79-71.
In the Men’s Super League, UCD Marian lost their unbeaten record when going down 91-66 at home to the in-form Killester.
Killester commanded a three-point interval to lead 40-37 and but amazingly the students were restricted to eight points in the final quarter as their opponents outscored them 28-8.
In the Women’s Super League, champions Liffey Celtics almost came a-cropper at home to Singleton’s SuperValu Brunell before eventually running out 66-65 winners.
The Cork side led for the majority of the game as coach Francis O’Sullivan was to left to rue a missed opportunity.
Ambassador UCC Glanmire travelled to NUIG Mystics and came away with a hard-earned 76-70 win.
Despite trailing 46-35 at the break, the westerners dug deep in the second half as Glanmire coach Mark Scannell reflected on their third consecutive win. Scannell said: “I said leading up to this game that the league has improved and it’s always going to be hard for us as we are competing against two Americans on a weekly basis.”
Killester were also pushed hard at Clontarf before disposing of Portlaoise Panthers 78-64 with American Stephanie Poland leading their scoring on 17 points.