Przemyslaw Placheta struck a superb winner to give Oxford a shock 2-1 victory over in-form Ipswich and their first win in six Sky Bet Championship matches.
Mark Harris fired the Us in front in the 28th minute with his first goal of the season when he seized on a poor pass from Azor Matusiwa and beat Christian Walton at the second attempt.
Leif Davis equalised for Ipswich in the 53rd minute, volleying home unmarked from the edge of the area after Marcelino Nunez picked him out with a pinpoint outswinging corner.
But substitute Placheta broke clear on the right from Brian De Keersmaecker's ball out of defence in the 77th minute, finishing clinically from 20 yards to lift his side out of the relegation zone .
Town, who could have moved up to second, had come into the game in fine form on the back of three straight away wins.
Oxford head coach Gary Rowett, unable to call on his star midfielder Cameron Brannagan who is out until the New Year with a calf injury, rewarded Filip Krastev for his late equalising goal at Norwich on Tuesday with a starting place.
It was Town who engineered the game's first real chance with Sindre Egeli firing low past the post from 15 yards from Davis's pass.
Jaden Philogene was often the outlet for the visitors on the left touchline and from one of his bursts into the box, and then a cross from the overlapping Davis, Egeli headed against the outside of the post on 21 minutes.
It was out of the blue when Harris latched on to sloppiness at the back by Matusiwa to put United in front.
The goal lifted the crowd and with the stadium now more noisy, De Keersmaecker struck a powerful left-foot shot that brought Walton to his knees.
Ipswich rallied after the break and when Davis volleyed in Nunez's corner to make it all square, Town's players suddenly had an extra spring in their step.
Oxford 'keeper Jamie Cumming became a busy man, turning Philogene's shot past his left post, beating out a Nunez piledriver and spreading himself to deny George Hirst from close range.
But Oxford found a second wind as Walton had to save from Will Lankshear and after Placheta's goal, Ole Romeny was a whisker away from making it three.
Oxford's Gary Rowett:
"If you're a No 9 and you're not scoring goals, of course you're going to come under fire and people are going to question why you are putting him in.
"But when you see him day in, day out, Sparky works so hard for the team, he's a selfless player, he presses brilliantly.
"He's looked confident in training and it's great to see him score. The rest of the players will be buzzing for him because they know how much he brings to the side.
"Przemy's got the pace to hurt any side, but with his goal it was a great pass from Brian [De Keersmaecker] and I thought his touch was good, and he finished it really well.
"We made a few changes, I felt we had to because it was a particularly tough week, to play Saturday, Tuesday, Friday. There were a few big calls - starting Sparky instead of Will [Lankshear] was one I toyed with all day.
"I was really disappointed with the goal we conceded, it was a good finish but too easy a goal to concede.
"And then there was a real decision to make - sit in and hang on for a point, or do we show a bit of quality and ambition, and character, and make changes to the way we were playing? For 10-15 minutes we stepped up really well.
"It's been a big week for us - two good draws and then a win against a well-coached side with some very good players."
Ipswich's Kieran McKenna:
"We weren't clinical enough in the phases of the game where we had control, and we've given away two poor goals that changed the momentum of the game and the energy in the stadium.
"It's frustrating because it feels a bit like we've given the game away, on the back of a pretty good run. But there was still plenty of the performance that was fine - the players never gave up, even at 2-1 down.
"In the second half once we had got level, it felt the only way Oxford were going to score was going to be on the counter or from a long throw. It came on the counter when we were pushing to try to get the winning goal, and we didn't deal with it well enough.
"Goals change games. Their first goal rocked us a bit, and it was the same for the second goal.
"It was frustrating that we didn't score more from the chances we had in the second half. We've been very clinical in our last few away games. Tonight we weren't, and it's cost us."
