Following a solid and impressive run of results, Hartlepool saved one of their worst performances for the table's bottom team.
Not for the first time this season, after getting to within sight of the play-off zone Pool let themselves down.
They went to Newport with the top seven in sight earlier in the season but never performed and were rolled over. It was the same story on this occasion.
The visitors never got going and the Cobblers’ workrate and direct approach was basic but too much.
A point at Southend last Tuesday was a good return, but they let down their standards.
Two goals either side of half-time broke Pool at the County Ground.
Both goals were given away cheaply and weren’t the sort they have been conceding of late.
The first, during six minutes of first-half added-on time, came after Darren Holden was harshly pulled up for a foul.
Chris Hackett’s cross into the area sailed to the far post, where full-back Joe Widdowson was allowed to run in without being picked up to nod the ball back across goal for Mathias Doumbe to turn in.
The added time was after Pool’s right-back Michael Duckworth was carried off with a suspected broken leg and play was held up while he was assessed.
He went home with his team-mates after x-rays didn’t show any break.
The second goal came a minute after the restart.
Hackett again crossed, this time from open play, and midfielder Brennan Dickenson turned in from close range.
Simon Walton fired a low shot against a post and Luke Williams – who returns to Middlesbrough today after an impressive month-long loan – finally forced a save from Matt Duke.
However, it wasn’t good enough and Cooper wasn’t going to try and convince anyone otherwise.
He said: “I will analyse it, but the discussion in the dressing room is a line drawn under it.
“All we can do is dust ourselves down and start again.
“We have a look and see if there’s anything visible.
“It seemed flat, some of the lads admitted to feeling that way. Now it’s my job to make sure we have a spark for the next game.’’
NORTHAMPTON: Duke; McSweeney, Diamond, Doumbe, Widdowson (Robertson 67); Hackett, Carter, Ravenhill, Dickenson; Sinclair (Connell 67), Marquis (Deegan 86). Subs (not used): Morris, Tozer, Snedker, German, Booked: Marquis.
Goals: Doumbe 45, Dickenson 46.
HARTLEPOOL: Flinders; Duckworth (Richards 11), Collins, Burgess, Holden; Barmby (Compton 66), Walton, Walker, Williams; James, Harewood (Franks 66). Subs (not used): Rafferty (gk), Monkhouse, Sweeney, Poole. Booked: Holden, Walton, Williams. Att: 4,083