Paul Cook admits Chesterfield were not at their best in their 3-1 win at Morecambe but he is already looking ahead to Tuesday's game at York.
Gary Roberts and substitute Armand Gnanduillet hit the second half goals as his promotion-chasing outfit came from behind to beat the Cobblers at Sixfields to leave King's side six points adrift.
Darren Carter gave the basement boys the first-half lead from the penalty spot after goalkeeper Thomas Lee hauled down Hallam Hope. But Chesterfield equalised through Dan Gardner before the break and after the restart Roberts notched his seventh league of the season before Gnanduillet added a third late on.
He said: "We have to win games to get promoted and we now have 19 big games, it's all about Tuesday night at York for us now. The fans have great belief in the team and I've told the players we have to repay that faith.
"We maybe had a bit of a hangover from Tuesday night and it was disappointing to go behind early to the penalty but you can never afford to feel sorry for yourself.
"You have to make results and you have to work to get them. Northampton never lied down and accepted it and that made it a big three points for us.
"We've made bad decisions in games and we had some luck in this game but if you work hard then you tend to find you get the little breaks in matches."