Cooper told the club's official website: "It wasn't about me and Darren (Ferguson), it was about Peterborough against Preston, 11 v 11 and on the night Preston won.
"(It was) probably a little bit against the run of play. I thought we deserved something out of the game, but it wasn't to be and we go again on Saturday.
"We've got to keep going, keep believing, see if we can find that little bit of quality in and around the final third of the pitch when we get in the box and go up to Crystal Palace and get three points."
George Boyd, who had been struggling with an ankle injury, managed the full 90 minutes and should be fit for the weekend. Chris Whelpdale and Aaron Mclean appeared to pick up knocks and, although Cooper will assess their fitness, he is hopeful they will also be available.