Dunfermline avenged their recent league defeat against the same opponents when they ousted Perthshire in the semi-final of the RBS Caledonia Shield.
The pair have been neck and neck in the league campaign with Perthshire now having the edge.
However, it was the McKane Park men who progressed to face Caithness for the silverware with a 15-3 win.
Dominic O’Connor nudged Perthshire into the lead with an early penalty but Gregor McNeish responded in kind for the Fifers then added a second kick for a 6-3 half-time lead.
And he proved to be the match winner with two further penalties and a drop goal.
Glenrothes will meet Stirling University in the final of the RBS Midlands Regional Bowl after posting wins over Hillfoots and Arbroath respectively.
Glenrothes produced what was widely regarded as their best performance in several years to inflict a first defeat of the season on the Tillicoultry men and atone for a heavy loss when the sides met on league duty.
The scoreline remained blank throughout a fiercely contested opening half hour and it was Glenrothes who finally broke the deadlock when scrum half Michael Delorey surged forward and offloaded to Ryan Venters who raced over for an unconverted try.
That left the Fifers 5-0 ahead at half time and although both sides had opportunities as the second half unfolded, the only addition to the scoreline was a penalty from Shaun Gray.
Meanwhile, the students had a more straightforward passage to the final, which will take place on February 15, seeing off Arbroath 36-0.
With Hillfoots engaged on knock out duty, Harris FP had the opportunity to close the gap on the RBS Caledonia Division 2 (Midlands) pacesetters.
And the Elliot Road men took full advantage, seeing off Panmure 69-0.
Andy Wallace and Greg Matthew had two tries apiece and Joe Abbott scored one, with Matthew adding two conversions as Harris reached half time with a 29-0 lead.
Mathew took his personal tally to 34 points with two further tries and five conversions, while Abbott touched down for a second time, and there was one apiece for Poloc Islam, Blair Smith and Louis Malhomme.
The win has moved Harris to within seven points of Hillfoots in the table, although they have now played two games more than the team in pole position.
Howe of Fife seconds tightened their grip on top spot Division 3 (Midlands) when they eased to a 41-12 success at home to Grangemouth seconds.
However, Blairgowrie remain in hot pursuit after seeing off Glenrothes seconds 33-0.
Carnoustie moved up to third spot after taking all five league points from a 35-8 win away to Waid Academy.
The Angus men trail the pacesetters by 10 points but have a game in hand.
They have replaced Crieff & Strathearn who had to settle for a share of the spoils with a 10-10 draw against Fife Southern at Braidhaugh.