Horspath's hopes of retaining the Hartwell Trophy were dashed with an eight-wicket defeat by Aston Rowant on the Duckworth-Lewis-Stern method in a rain-affected final at Challow & Childrey.
Making their fourth straight appearance in Oxfordshire's showpiece T20 decider, Horspath posted a competitive 146-8 after electing to bat.
Rowant's reply stood at 51-1 off six overs with Derval Green having produced a cracking delivery to bowl Chris Watling for 18 when rain forced the players off resulting in a 53-minute interruption and seeing the target revised to 99 off 13 overs.
With three overs remaining, Rowant required 27 to win, but then captain Tristan Rossouw, who averaged 133 in this season's competition coming into the final, hit two mighty sixes over long on to put his side firmly in the driving seat.
He brought up his half-century off 34 balls with two runs to backward square leg in the penultimate over before being trapped lbw for 51 attempting a reverse sweep off left-arm spinner Sam Leslie's next delivery. His fine knock also included four fours as he shared a second-wicket stand of 52 with Tom Condon (16no).
Rowant required four to win off the last over bowled by Green and despite the Jamaican's best efforts they got home at 99-2 when Condon scrambled a quick single with a ball to spare for a first final success.
It was a somewhat unsatisfactory conclusion to a contest which had seen Horspath, bidding to lift the trophy for a fifth time, recover from the loss of an early wicket with some positive strokeplay seeing Stephen Green and opener Tyron Eyles put on 57 in eight overs.
Green mixed some powerful cover drives with highly effective use of the reverse sweep, while Eyles pulled a six over mid-wicket to send the beer flying among the Horspath supporters as the boundaries flowed to the accompaniment of loud music.
Green made 31 off 24 balls when he lofted a drive off Sebastian Grocutt (2-30) to Rossouw at mid-off, sparking a mini collapse.
Two runs later, Eyles fell to Luke Hayes for 19 as Finley Little took a good catch falling backwards at long on.
It was soon 65-5 as Rossouw struck twice in the space of three balls and the holders were up against it.
However, Derval Green and Rob Wight batted sensibly to rebuild the innings with a sixth-wicket stand of 61 inside eight overs.
Green played the leading role with some powerful blows and deft touches. He smashed a six over mid-wicket before bringing up the 100 with a four which split two fielders at long on and then hammered another maximum over square leg.
The West Indian all-rounder was closing in on a half-century when he was caught by Watling at long on off Grocutt for an excellent 48 off 30 balls, making it 126-6.
Sravan Konidena (15no) peppered the pavilion with a six in Horspath's final flourish, which saw Wight's innings end when he was stumped by Jamie Revill for 16 as Rossouw finished with 3-34.
Rowant's run chase began in light rain with Watling and Rossouw unleashing a flurry of boundaries to put them in the ascendancy before the break in play led to a revised target.
And that just proved insufficient for Horspath to defend in a tight finish on a day when events rather conspired against the side.