Chris Wilder criticised his Oxford side after they were held to a goalless draw by Accrington.
James Constable twice went close for the Us in what was the clubs' first-ever meeting but the match never really took off as a spectacle, with forwards continually getting caught offside.
"We were poor and didn't deserve to get anything out of the game," said Wilder
"It's been a strange start to the season for us because the standards have been spot on, but today our decisions were poor, our forwards never got hold of it, we were poor at anticipating - everything was a reaction.
"We also never got tight and when we got the ball we kept giving it away. So it was a real head-scratcher for me. Mentally and physically we looked very tired, and that's part of our game that we have good energy levels in our team. It's something we've definitely got to look at."