Two spectacular tries by Romanian international Mihai Viorneau and an equally exuberant try by scrumhalf Mark Cross were not enough to stop Lansdowne scrapping the points at Kilternan on Saturday.
Lansdowne scored two more mundane tries but the boot of outhalf Alan McGowan, their more determined rucking and eventual lineout superiority, sealed the issue by a lucky whisker.
In the second half, especially, Lansdowne's more organised defence in midfield closed down the dangerous-looking three quarter attacks mounted by DLSP.
The match started with a flourish. From the kick-off, DLSP won a clean lineout, but from scrappy midfield ball, Critchley picked up, broke through the tackles and fed Cross, who squirrelled over in the corner.
Critchley missed the difficult conversion. On 10 minutes, McGowan blocked down a late clearance attempt by DLSP fullback Eddie Devitt and raced through for the easy touchdown and also converted.
Then came the first of Viorneau's spectaculars. From loose ball off the kick-off he took a quick pass from Critchley, broke the cover from 30 metres out, chipped over fullback Eddie Devitt, and bravely dived under the covering defenders to touch down.
Lansdowne hit back with a soft try by Anthony Ronan after sloppy lineout work by DLSP. McGowan's conversion and penalty left the half-time score 20-12 for Lansdowne.
Viorneau's second try earned DLSP a two-point lead but McGowan's 30-metre penalty 10 minutes from time sealed victory.
SCORING SEQUENCE: 1 min: Cross try 5-0; 10: McGowan try, con, 5-7; 13: Viorneau try, Critchley con, 12-7; 28: McGowan pen, 12-10; 32: Ronan try, McGowan con, 12-17; 43: McGowan pen, 12-20; 45: Critchley pen, 15-20; 57: Viorneau try, Critchley con, 22-20; 70: McGowan pen, 22-23.
DE LA SALLE: E Devitt; M McGuinness, J Critchley, D O'Riordan, M Viorneau; S Broughton (capt), M Cross; E Moore, A Davis, D Masters, P McDonnell, R Candlin, S Tynan, S McCarthy, J Deen. Replacements: S Sarsfield for Tynan, C Condron for Moore (both 63 mins).
LANSDOWNE: B Doherty; R Dolan, L O'Brien, R Kearns, F Baynes; A McGowan, S Whelan; E Boland, A Ronan, A McKeen, B Cusack, S O'Connor, S Rooney (Capt), L Toland, A McCullen. Replacements: B Geraghty for O'Brien (31 mins).