Chris Wilder was at a loss to explain how his Oxford side failed to break down Torquay in a 0-0 draw at the Kassam Stadium.
United took control after a dour first half but passed up a host of late chances to take the points.
"I'm struggling to work out how we've not won that game," said Wilder.
"We were all desperately disappointed by our home defeat against Dagenham on Tuesday but this was a much better performance. We didn't play like a team in the lower reaches of the division.
"Yes, we should have been more clinical. But we showed a positive attitude from the first minute on in trying to win the game.
"On Tuesday we didn't do enough, but we did enough today. Torquay won't have had a sterner examination away from home all season."