Development Cup finalists CBS Wexford came within a whisker of causing a massive upset against Skerries Community College at Dr Hickey Park.
Skerries eventually prevailed 25-21 after a rip-roaring tie in which the Wexford boys jumped out to an early lead with tries by fly-half Eoin Roche and Ireland Clubs forward Collie Joyce-Ahearne, who was operating at No 8.
They went 21-13 ahead when Roche arrived on cue for his second try in the 37th minute, wing Sean Stafford converting for the third time.
However, Wexford just could not cope with rampaging Skerries No 8 Evan Sherlock, who scored a hat-trick of tries, two in the first half and the another after the break, which catapulted the North County Dubliners into the lead in the last quarter.
Meanwhile, scrum-half Kevin Burke accounted for all De La Salle's points as they edged out The High School 13-12 at Lakeland's Park.
It was just about enough to resist High School's effort, which was driven by tries from hooker Tim Harding and flanker Gavin Power.
St Gerard's had it almost all their own way in a resounding seven-try 48-3 dismissal of Templeogue College at Seapoint RFC.
Con Callan and Sam Kingston both grabbed a brace of tries as Tommy Whittle showed good form with the boot, kicking five conversions.
St Andrew's made better use of the ball to clip CUS 11-0 at Merrion Road, where right wing Luke de Renzy slotted two penalties in the second and 10th minutes and left wing Stephen Keenan powered into the corner in the 44th minute.
Centre Daniel Gill struck for two tries in Mount Temple's 27-20 win over St Patrick's Navan at Westmanstown.
Full-back Ben Warren got another and the fourth came from fly-half Daragh Irwin, who also landed a drop goal and two of four conversions.
At Merrion Road: St Andrew's 11 (S Keenan try; L de Renzy 2 pens), CUS 0.
At Lakeland's Park: De La Salle, Churchtown 13 (K Burke try; 2 pens, con), The High School 12 (T Harding, G Power try each; Dean Kilroy con).
At Seapoint RFC: St Gerard's School 48 (C Callan, S Kingston 2 tries each; M Prendergast, C Kenny, A Simmonds try each; T Whittle 5 cons; D Baker pen), Templeogue College 3 (E Clynes pen).
At Dr Hickey Park: Skerries CC 25 (E Sherlock 3 tries; P Lacey try; B Mulcahy pen, con), CBS Wexford 21 (E Roche 2 tries; C Joyce-Ahearne try; S Stafford 3 cons).
At Westmanstown: Mount Temple 27 (D Gill 2 tries; D Irwin try, dr gl, 2 cons; B Warren try), St Patrick's Classical 20 (M Dunne, S Faulkner, E McGrane try each; C Farrell pen, con).