Cobblers started their Leasing.com Trophy campaign with a penalty shoot-out victory over 10-man Arsenal Under-21s at the PTS Academy Stadium on Tuesday evening.
The young Gunners had a man sent off on the hour-mark but they then led through James Olayinka's tap-in, only for Sam Hoskins to level things up with a fine finish seven minutes from time.
That forced a shoot-out and it was Town who claimed the extra point on offer.
Andrew Fisher, on his debut, saved Arsenal's first spot-kick and successful efforts from Hoskins, Shaun McWilliams, Ryan Watson and Billy Waters put pressure on Emile Smith-Rowe to score his attempt, and he couldn't deliver, blazing over the crossbar.
That handed Town a 4-3 victory in the shout-out and gave them two points to start their Southern Group H campaign in the EFL Trophy.
Keith Curle named a surprisingly strong side to face Arsenal's youngsters, with Charlie Goode, Jordan Turnbull and Watson all starting, while newly-signed goalkeeper Fisher made his debut.
Despite Curle suggesting he would feature several young players, Scott Pollock was the only teenager to start although Morgan Roberts and Jay Williams were on the bench.
For the third game running Town were involved in a dour and lifeless first-half that served up very little in the way of goalmouth action.
Arsenal's Nathan Tormey was a lively figure on the left-wing throughout and his electric pace gave Cobblers' back four some tough moments, most notably when he cut inside and forced FIsher to tip wide of the post.
At the other end, Hoskins was Town's most dangerous outlet and he went as close as anyone to the breakthrough when intercepting a loose pass and firing into the gloves of Matt Macey.
Otherwise, the first-half was a tough watch and it continued be the same in the early stages of the second-half, although Trae Coyle did force Fisher to tip over with a long-range effort and Tormey drilled into the side-netting.
The visitors were beginning to see more and more of the ball but their hopes of victory were dealt a major blow just past the hour-mark when Tobi Omole, on a booking, mistimed a challenge on Hoskins and promptly saw red.
Cobblers almost made their man advantage count immediately as Macey saved from Hoskins and Waters shot into the side-netting before Matty Warburton swept wide of the far post.
But it was Arsenal who took a shock lead with 13 minutes remaining when Smith-Rowe got away down the left and squared a low cross for the unmarked Olayinka to tap home at the far post.
The lead lasted just four minutes, however, as Town swiftly hit back through Hoskins, who expertly picked out the top corner with a precise volley following Vadaine Oliver's knockdown in the box.
Chris Lines almost won it, flashing over from 30 yards, but it took a shoot-out to separate the sides and Smith-Rowe's wayward effort saw Cobblers claim the bonus point.
Cobblers: Fisher, Goode (c), Turnbull, McWilliams, Bunney, Watson, Pollock (Lines 70), Warburton (A Williams 84), Waters, Hoskins, Smith (Oliver 73)
Subs not used: Cornell, Adams, J Williams, Roberts
Arsenal: Macey, Bola (Omole 31), Clarke (c), Coyle, McEneff (Burton 73), Olayinka, Olowu, Swanson (Ogungbo 84), Tormey, Smith-Rowe, Balogun
Subs not used: John-Jules, Hillson, Azeez
Referee: Robert Lewis
Arsenal fans: 599