Oxford boss Chris Wilder revelled in claiming an important three points with a 2-1 win over Rotherham.
Rotherham had defender Callum Kennedy, who was making his debut, sent off as they lost a fifth away game in a row.
Oxford took the lead through Simon Heslop but the Millers equalised when Nicky Law nipped in ahead of U's keeper Ryan Clarke. Steve MacLean then converted from the penalty spot after Kennedy had brought him down to seal the victory. Kennedy was dismissed for a professional foul on MacLean.
Wilder said: "We want to make this a difficult place to come.
"If we can get at sides here and an atmosphere that is positive and driving us forward, we've got an interesting end of the season to come.
"We must have had at least 15 good shouts for a penalty here this season and this was only our second one.
"I should have been lighting up a big fat cigar with 15 minutes to go with the chances we had to put it out of their reach."