Barnsley were made to pay for their inability to finish chances against a clinical Hornets side who will now get a second bite of the cherry in a fortnight's time.
In a topsy turvy encounter at Oakwell on Friday night, the Reds will be hugely disappointed not to have seen off non-league opposition in the first round of the Emirates FA Cup.
After a pretty uneventful opening 10 minutes, the Reds sprung into life and Max Watters put us in front. A great cross from the left wing by Jamie McCart was headed home by our number 36 from close range.
It could have been two within minutes when Watters glanced another effort just wide after Corey O'Keefe had sent in a low cross to the front post.
But on 22 minutes, the visitors stunned Oakwell with a leveller.
Great play on the left flank from Daniel Ajakaiye saw him tee up Shamir Fenelon who sweeped home a wonderful finish, first-time into the far corner.
Callum Styles saw a drive parried behind by Lewis Carey and Fábio Jaló was also denied by the goalkeeper with a great one-handed stop from 12 yards out.
The away side, from the 7th tier then took an unlikely lead.
A penalty was awarded after a challenge just inside the box and up stepped James Hammond to fire down the middle and send the 500+ away crowd into raptures.
With seconds remaining in the first half, we responded well as Jalo was again scuppered by the efforts of Carey to his right-hand side, six yards out, but bang on the stroke of half time, our 17-year-old starlet did find the goal he'd been threatening.
An outstanding effort, curled into the top corner from just outside the box, tying the contest heading into the interval.
HALF TIME: Barnsley 2-2 Horsham
Whilst still dominating the ball and creating most of the chances, it was still pretty flat stuff from Neill Collins' side despite the break, with little of not registered in the opening 10 of the second 45 minutes.
Owen Dodgson tried something from range that was heading for the top corner only for the inspired Carey to tip the ball behind for another corner kick.
And just a few minutes later, our pressure paid off. From another corner, Maël de Gevigney headed home at the near post.
There was a raft of substitutions from both sides and the game seemed to be drifting towards a Reds victory, as they continued to set up camp in the away side's half.
Luca Connell made his long-awaited return to fitness, and he, Styles and McAtee were all unable to finish off a Reds move, all seeing shots thwarted by the 'keeper or blocks from defenders with efforts from in and around the box.
With just 10 minutes to play, the visitors broke on the counter and the wide man pulled back across goal for substitute Tom Richards to tap home and again spark scenes of pandemonium in the away end.
Barnsley had numerous chances to find a winner, but Adam Phillips - twice - and Styles wasted great chances to end the contest right here tonight.
As it is, we'll be heading to Sussex for a replay in a couple of week's time.
FULL TIME: Barnsley 3-3 Horsham
Killip, O'Keeffe (Cotter), Williams, de Gevigney, McCart, Dodgson (Cole), Kane (Phillips), Styles, McAtee (Connell), Watters, Jaló (Cadden).
Unused: Flavell, Shepherd, McCarthy, J.Benson.
