Asad Rafiq returned Home Counties Premier Cricket League-best figures of 6-48 - but it wasn't enough to prevent Horspath's 10-match unbeaten run in Division 2 ending with a 37-run defeat at home to Chesham.
The seamer produced a terrific opening burst to reduce the Bucks club to 43-4 after they chose to bat only for them to recover to post 241 all out off 50 overs.
Horspath were well set to knock off the runs at 154-4, but then a collapse set in as the hosts crashed to 204 all out, with crucially 46 balls not used.
A first loss since a four-wicket defeat at Wokingham on May 31, it's a blow to the side's promotion push as they drop to fourth with the gap to second-placed Wokingham now 26 points.
Asad's brilliant spell saw him strike with consecutive deliveries at the start of his second over as Moiz Rana and Ranvir Sinha both edged to Tom Nichols at first slip, the second one a sharp low catch to his left, making it 9-2.
Mark Eteen attempted to steady the ship, but Asad produced another cracking delivery with his brother and captain, Amin Rafiq, taking a good low catch to his right to leave Chesham 39-3.
The Horspath paceman was bowling superbly and he added to his tally when Daksh Sabheral was lbw.
Opener Matt Rance had stood firm, though, and in Andy Goddard he found a willing ally as the pair turned the innings round with a partnership of 99 for the fifth wicket.
Rance went to his fifty with a four through the legside and had moved on to 61 when he was bowled by Viv Narayan. His runs came off 112 balls and included seven fours.
The leg-spinner enjoyed more success when Kieran Patel was caught in the deep by Tom Coleman, and when Goddard was bowled by Amin for 42, Chesham were 154-7.
But then Jason Rance smashed 65 off 36 balls to power the visitors to their final score, adding 45 for the eighth wicket with Kamran Khan.
Asad returned to bowl Khan for 14 and complete his first Home Counties five-wicket haul - and second this season after picking up 6-21 against Aston Rowant in the Village Cup.
Rance raced to his half-century with a boundary, before Asad made it six wickets by shattering Moteeb Syed's stumps.
However, Rance, with seven fours and three sixes, ensured Chesham's innings finished with a flourish before he was caught by Amin off Derval Green's last ball of the innings.
Narayan picked up 2-34, while Amin returned fine figures of 1-25 off 10 overs.
Nichols and Sravan Konidena, fresh from last week's record-breaking opening partnership of 182 at Gerrards Cross, got Horspath's run chase off to a solid start with 42 off the first nine overs only to both fall on that score in the space of six balls.
Konidena was first to go for 21, miscuing an on drive against Jason Rance to be well caught low down at mid-off by Jonathan Burden, who then trapped Nichols lbw for 19.
Narayan and Tom Coleman added 53 for the third wicket, before the former was bowled by Rana for 22.
Coleman also shared a half-century stand with Green, putting on 52 for the fifth wicket. The Jamaican hammered three sixes in making 32 off 17 balls before holing out to Jason Rance at long off with Rana the successful bowler.
That triggered a collapse with five wickets going down for 17 runs - including Coleman for 23 - as Horspath slumped to 171-9.
Amin was joined by Liam Turnbull in a last-wicket stand of 33, before the captain was caught at cover by Eteen off Khan for 26. Rana (3-46) was well supported by Khan (2-23), Burden (2-37) and Syed (2-38) as Chesham secured victory.
Horspath will seek to get back on track on Saturday when they visit relegation-threatened Falkland, who lost by two wickets to promotion-chasing Gerrards Cross.
Match highlights are available by clicking here