Max Sorensen was the most successful of the quartet of Irish international bowlers used by Lightning skipper John Mooney - he resisted the temptation to use himself - as the Northern Knights were dismissed for 174 replying to Lightning's first innings total of 337.
Sorensen picked up the wickets of James McClurkin (4), stand-in Knights skipper James Shannon (8), and Peter Eakin (22) to finish with 3 for 49.
George Dockrell kept a tight grip on the Knights batting, conceding just 21 runs in 13.1 overs, while dismissing James Cameron-Dow (21) and the last wicket to fall - Stephen Bunting, stumped by McAllister for 3.
Shane Getkate top scored with 36 before becoming Tyrone Kane's second victim, while James McCollum hit five boundaries in an entertaining 30 before being bowled by Eddie Richardson . That first wicket of the day started the Knights' collapse as 9 wickets fell for 102 runs as the Lightning attack took a complete stranglehold on the game.
Mooney opted not to enforce the follow-on and openers Fintan McAllister and Jack Tector took a safety-first approach in the 16 overs before tea, taking the score to 48 for 0, and the overall lead to 211.
The cautious approach changed dramatically post-tea as a flurry of boundaries saw a further 143 runs added in just 14 overs.
Malahide opener McAllister was the dominant force, striking 16 fours and a six in an unbeaten 105 from just 95 balls. He shared an opening stand of 147 in 155 balls with debutant Jack Tector - the YMCA teenager made 57 from 76 balls (4 fours, 3 sixes) as the Knights attack wilted in the face of the fierce onslaught.
The declaration on 191 for 1 came with Lightning 354 ahead and 15 overs remaining in the day - which bad light abbreviated to 10.
James McCollum (21) fell in what ultimately proved to be the penultimate over of the day - trapped in front by Max Sorensen (1-15) as the Knights ended the day on 33 for 1.
The destination of the Championship will be decided on the final day with Knights needing an improbable further 322 runs and Lightning a more likely 9 wickets. If the weather intervenes, then a draw would see the title going to the NW Warriors. All to play for on what promises to be a fascinating denouement to the Inter-Provincial season.
HANLEY ENERGY INTER-PROVINCIAL CHAMPIONSHIP
At Rathmines, Day 2 close of play
LEINSTER LIGHTNING 337/9 dec and 191/1 dec (30 overs, F McAllister 105*, J Tector 57)
NORTHERN KNIGHTS 174 all out (68.1 overs, S Getkate 36, J McCollum 30, P Eakin 22, J Cameron-Dow 21, C Dougherty 20, M Sorensen 3-49, G Dockrell 2-21, T Kane 2-25) and 33/1 (10 overs, J McCollum 21, M Sorensen 1-15)
