Ritchie Humphreys's first-half strike was enough to see Chesterfield keep their four-point lead at the top of League Two by beating Oxford United.
United started the game in second place, but were unable to break down the Spirites defence despite plenty of opportunities throughout the game.
The winning goal came on the half-hour mark when Eoin Doyle delivered an inch-perfect cross for Humphreys, who directed his effort across U's keeper Ryan Clarke.
It capped an eventful 24 hours for Humphreys, who witnessed the birth of his second child yesterday.
Oxford's hopes of a second-half comeback seemed to be finished when Andrew Whing was sent off for a late sliding challenge on Doyle on 67 minutes.
However, the U's and Deane Smalley continued to threaten and could have equalised late on when he met Dave Kitson's cross, only to be denied by the foot of the post.
The result means that Chesterfield are four points clear of Fleetwood Town, while Oxford slip out of the automatic promotion places having lost their unbeaten record.
