Cobblers are guaranteed a home tie against another League Two outfit in the second round of the FA Cup should they beat Cambridge United in next week's replay.
Either Bradford City or Exeter City will make the trip to Sixfields next month.
Ties in the second round are to take place across the weekend of Friday, December 3, through to Monday, December 6.
Cobblers and Cambridge will face off in a replay at the Abbey Stadium next Tuesday following their 2-2 draw on Saturday.
Bradford and Exeter must also play each other again after drawing 1-1 at Valley Parade at the weekend. Sam Nombe scored a late goal to cancel out Theo Robinson's opener.
Exeter are currently one place below Northampton in fourth in League Two, while Bradford are down in 12th.
Cobblers are due to face both teams in the league over the next few weeks.