The Cobblers' record-breaking unbeaten Football League run is over after they were beaten 3-1 at Chesterfield on Saturday afternoon.
Town went into the game on a high after successive home wins and unbeaten in 31 League matches, but they were second best for most of the afternoon at the Proact Stadium as Chesterfield claimed their first win since August 16.
Two goals from Conor Wilkinson, the second via a huge deflection, and one from Dion Donohue condemned the Cobblers to their first league defeat since they lost to Portsmouth on December 19, 2015, with Paul Anderson's first goal for the club proving little more than a consolation.
The loss was also Northampton's first on the road since they went down 2-1 at Cambridge United on October 17 last year, and they have dropped to 11th in Sky Bet League One as a result.
The Cobblers once again named an unchanged team for the clash, with the bench also the same as it was for the 2-0 win over Walsall at Sixfields, while Chesterfield were dealt a blow as their top scorer Ched Evans was ruled out through injury.
Both sides were guilty of giving away possession far too easily in the early exchanges, and it came as something of a surprise when the home side took the lead after just eight minutes.
It was a frustrating goal to concede too.
Jon Nolan played the ball out to the left wing to Kristian Dennis who was in an offside position, and Zander Diamond hesitated waiting for the flag.
But with the assisant set to raise his flag, Dennis left the ball and Conor Wilkinson running outside him - and onside - picked it up and raced into the left side of the penalty area before driving a low shot across Adam Smith and in off the post.
The goal meant the Cobblers trailed in a league match for the first time this season.
Town responded well to going behind, but never tested home goalkeeper Ryan Fulton as a Matt Taylor drive that flew over the bar was their best effort.
Chesterfield were clearly buoyed by their early goal, and they could have made it 2-0 on 24 minutes but Diamond produced a fantastic clearance from underneath his own crossbar to deny Dennis, who was waiting to pounce for a simple finish.
Diamond was at the heart of things from a Town defensive view, and he produced a great tackle on Wilkinson as the Spireites man was about to pull the trigger from 12 yards, and a goalbound shot from Dennis then smashed into the Scotsman's chest.
As the half came to a close, the Cobblers at least managed to pose an attacking threat, and Chesterfield's Sam Hird did brilliantly to block a volley from Harry Beautyman after a knockdown from Alex Revell.
Fulton was then forced into his first save of the afternoon, tipping over a powerful Taylor shot from 20 yards, but it stayed 1-0 at the break.
Manager Page made a change at half-time, Kenji Gorre being replaced by Sam Hoskins, and he will have wanted his team to start the second half on the front foot, but within four minutes they were 2-0 down.
Wilkinson was allowed to drift in on to his left foot, and with no pressure on the ball he had a crack from 20 yards with his left foot.
The effort was heading goalwards, but hit Diamond and flew into the opposite side of the goal, leaving Smith with no chance. The deflection was unfortunate, but Wilkinson was given too much time and space.
On 61 minutes, Page reacted positively to the setback and brought on Marc Richards to replace Beautyman as Town went 4-4-2, and the move paid instant dividends as the visitors reduced the arrears two minutes later.
Taylor's left wing cross was met at the far post by Anderson, and although his volleyed connection wasn't the cleanest, the ball went beyond Fulton and into the bottom corner.
Town were now in the ascendancy and applying pressure, but they shot themselves in the foot on 70 minutes.
On the attack, Brendan Moloney surrendered possession with a terrible pass to Jak McCourt, and the home side launched a counter-attack that ended with Dion O'Donohue hammering home a left-foot shot from the left edge of the penalty area and across Smith to make it 3-1.
The Cobblers never gave up the ghost and battled to get back in the game again, but they failed to create any clear-cut chances, with their best effort a towering header from Revell that flew over the bar.
Town's players now have to lift themselves after this rare defeat, and with the little matter of Wednesday night's EFL Cup clash with Manchester United next up, that shouldn't be a problem.
Chesterfield: Fulton, McGinn, Hird, Liddle, Nolan, Donohue, Dennis, Anderson, Wilkinson, O'Shea, Aryibi. Substitutes: Evatt, Mitchell, Dimaio, Graham, German, Gardner, Parkin
Cobblers: Smith, Moloney, Diamond, Nyatanga, Buchanan, McCourt, Taylor, Anderson, Beautyman, Gorre, Revell. Substitutes: Cornell, Richards, Zakuani, Hooper, Hoskins, Potter, O'Toole
Referee: Robert Jones
Attendance: 5,910 (Cobblers fans 736)