It was Yorkshire's first day-night match and, while it brought in 10,000 fans, it turned into a huge embarrassment for the White Rose outfit as Lancashire turned on the power.
Chapple did most of the damage with a career best 6-25, but both he and coach Dav Whatmore underlined the victory as a team effort.
Whatmore said: Chapple was superb, but the lads knew how important it was to win this match and they all responded.''
John Crawley warmed up for the Foster's Oval Test against Sri Lanka with a hard-earned 73 on a tricky pitch and Neil Fairbrother and Andy Flintoff provided quick runs in a total of 182-8. And Warren Hegg hung on to five catches.
Lancashire now have a four points lead with two matches left against Hampshire and Notts. Second-placed Essex have a match in hand but Chapple said: ``The pressure is on them - they can't afford any slip-up.''
Crawley, likely to play at the Oval in place of the injured Nasser Hussain, and Mike Atherton link up with the England squad today.
But the rest of the side can enjoy a week's break before the final push for a history-making treble. It starts next Tuesday with a championship match against Derbyshire, followed by the NatWest Trophy final.