Oxford manager Chris Wilder was left to rue his side's missed chances as they were dumped out of the Johnstone's Paint Trophy at Aldershot.
Danny Hylton drove in a 14-yard shot from Wade Small's pass in the 17th minute to give the Shots the lead, and Damian Spencer wrapped it up 13 minutes into the second half, capitalising when Oxford defender Jake Wright dithered in front of goal.
Wilder said: "Goals change games, don't they? We could have been 2-0 up before they'd really had a kick because Matt Green was though, and Alfie Potter went through and hit the bar.
"Finishing is a massive part of the game, and if you don't get that part of it right, you're always going to struggle to win games.
"That's why I've brought in Tom Craddock from Luton. He's a proven goalscorer and he will helpfully solve some of our problems at the moment, because otherwise we're all right and playing well.
"It's just the final ball, when we've got into a good area, and not putting the chances away, that is letting us down."