Aldershot boss Dean Holdsworth says Oxford had too much quality as they defeated his side 2-1 in the Johnstone's Paint Trophy second round.
Deane Smalley and Robert Hall scored for the Us, with Danny Hylton pulling one back for the Shots, who slumped to a third straight defeat.
Holdsworth said: "Oxford punished us in the first 10 minutes of the second half. Other than that I thought it was quite even.
"I thought we might have edged the first half with the chances we had. It was going to take some quality, but Oxford had the quality. We had a lot of desire and a lot of effort but on the night our quality let us down.
"We have got players who are trying to perform to the maximum of their ability in a tough division and there won't be an easy game this season.
"There is a learning curve. Smalley came from Chesterfield who won the league last season. We can't buy players like that for £50,000 or £60,000 and that's where we are. If we want to do well we have to get the best out of our players."