Chiswick Griffin won the Battle of Chiswick to land the Riverside Challenge Trophy on Sunday.
But they needed a late equaliser and extra-time to overcome Chiswick Albion in the final at Bedfont FC.
Brimming from last week's League Cup Final win, Albion took the lead through Eugene Nouril, which looked enough for victory.
But Griffin, missing captain Jeff Lovell and prolific goal-getters Ben Fox and Gabs Jones, came back with 10 minutes left when Dwayne Rhone equalised from an uncleared corner.
Griffin could have won it in normal time, with Rhone missing a great chance for a second when one-on-one, and Ryan Russell finding the side-netting.
But they took the lead for the first time in the first half of extra-time when Mark Hartnett latched onto a long clearance from keeper Simon Greening to poke the ball home.
Harnett then set up Richard Kell, who hit the inside of a post, before being denied a chance for his second when the ref failed to play advantage when he would have been clear.
It was then Albion's turn to hit the woodwork, with Liam White's header from a Rob Ursell free-kick striking the post before rolling along the goal-line.
But it was Griffin who instead grabbed a third, with Russell taking advantage of Albion keeper Rob Dawson being up in attack to dribble the ball almost the length of the field before tapping into an empty net.
However, Albion could have the last laugh by landing the Chiswick & District Sunday League Premier title.
They are two points off the top with three games in hand, while Griffin would have to win their last two games and hope Albion drop points to be in with a shout.