Oxford first-team coach Andy Melville believes his side's character was crucial in the 2-1 win over Chesterfield.
Ian Morris put the home side in control before second-half strikes from Tom Craddock and Steve MacLean gave Oxford their first win in six games.
Melville said: "We showed great team spirit and there were some really strong performances out there.
"I thought we took care of the ball better in the second half because we gave it away cheaply at times in the first but it's a great result and reward for all the hard work we put in.
"It's not all about formations, it's about being a team on the pitch and getting second balls and winning battles. Everyone stuck together. We said to the players at half-time to keep believing and in the second half we really got on it.
"We said to keep working hard and to be fair to them they were different class. We worked hard as a group and that was a major part of it because you can't go out playing individually. This was a real positive for everyone connected with Oxford United."