Northampton lost 2-0 at home to Peterborough United in their Leasing.com Trophy opener.
After beating the Arsenal juniors on penalties in their tournament opener, the Cobblers were beaten at home by their Nene Valley rivals.
First half strikes by Idris Kanu and Siriki Dembele put the visitors ahead and on their way to the win.
The hosts also suffered injury blows during the match, with Ryan Watson forced off with a broken collarbone and Matty Warburton also subbed off through injury.
A smattering of early chances were enjoyed by both sides. For the hosts, Warburton saw a drive denied by Christy Pym, while at the other end, Peterborough’s Louis Reed cracked a free-kick off the post.
Pym then denied Harry Smith and the worth of that save would be proven as Peterborough bagged a quickfire double.
First, Kanu bundled home after a Peterborough corner, before Dembele ran through the away defence and scored a second.
Northampton still had chances, with Chris Lines having a shot saved and Smith heading off target.
The second half ended up seeing less momentum for the hosts, not helped by Warburton and then Watson both leaving the field injured.
Peterborough would have a scattering of chances, with Kanu and Dembele their closest tries, but the visitors had done enough to take the points.
Northampton will wrap up their group stage stint with a match against Cambridge United away from home in October.