A classy Swindon side dominated possession early on, but once the Cobblers got themselves into gear they more than matched their visitors.
In a real ding-dong battle, there were stacks of chances at both ends, with Tyreece Simpson opening the scoring on 57 minutes, only for Horsfall to cancel it out seven minutes from the end.
There was controversy too as referee Brett Huxtable disallowed Danny Rose's first-half goal after initially awarding it.
All in all, a belting contest. Here are our ratings from Sixfields.
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Danny Rose is all smiles after thinking he had opened the scoring against Swindon. Only for the goal to be chalked off moments later (Pictures: Pete Norton) Photo: Pete Norton
. Liam Roberts
For all of Swindon's possession, Roberts wasn't actually called into action too often. But when needed, he made one absolutely crucial stop from Tyreece Simpson to keep it at 1-0... 7 Photo: Pete Norton
. Aaron McGowan
The right-back enjoyed an excellent afternoon. Solid in defence and always an outlet in attack. Won the corner that led to Fraser Horsfall's equaliser and crossed the ball for Danny Rose's disallowed effort... 8 Photo: Pete Norton
. Fraser Horsfall
The skipper came up with the goods with that late equaliser, but he has had better days when it comes to defending. Couple of second-half lapses almost proved very costly... 7 Photo: Pete Norton
. Jon Guthrie
Guthrie and defensive partner Horsfall certainly had their hands full with Tyreece Simpson, and although the Swindon man got his goal, Guthrie's last-gasp tackle on the striker to deny him a winner in stoppage time was perfection... 7.5 Photo: Pete Norton
1. Liam Roberts
For all of Swindon's possession, Roberts wasn't actually called into action too often. But when needed, he made one absolutely crucial stop from Tyreece Simpson to keep it at 1-0... 7 Photo: Pete Norton
2. Aaron McGowan
The right-back enjoyed an excellent afternoon. Solid in defence and always an outlet in attack. Won the corner that led to Fraser Horsfall's equaliser and crossed the ball for Danny Rose's disallowed effort... 8 Photo: Pete Norton
3. Fraser Horsfall
The skipper came up with the goods with that late equaliser, but he has had better days when it comes to defending. Couple of second-half lapses almost proved very costly... 7 Photo: Pete Norton
4. Jon Guthrie
Guthrie and defensive partner Horsfall certainly had their hands full with Tyreece Simpson, and although the Swindon man got his goal, Guthrie's last-gasp tackle on the striker to deny him a winner in stoppage time was perfection... 7.5 Photo: Pete Norton