A far-post header by left back Kevin Sandwith brought Oxford United the double over Wrexham, who used to be their bogey side, as Chris Wilder's men finished their home programme on a high note.
The U's end with the second-best home record - 16-4-2 - in the Blue Square Premier. They could even finish with the best, if champions Stevenage lose to York on Saturday.
There were eight minutes to go when Sandwith peeled off at the back post and his downward header from Damian Batt's cross bounced down and over Wrexham keeper Chris Maxwell.
That brought a spurt of late action, with Alfie Potter only denied a second goal by a poor touch as he ran through on goal, and then Jack Midson chipped the keeper, but put too much on the shot.
United, who had also won 1-0 at the Racecourse Ground in north Wales, therefore made it five clean sheets in a row.
Going forward they weren't at their most fluent, but manager Chris Wilder had made a number of changes, so it was perhaps not surprising that there wasn't the same rhythm as with his first-choice XI against Mansfield last Saturday.
Oxford had most of the play and they also went very close to scoring in the 72nd minute.
After good work by Dannie Bulman, who had just come on as a sub, Matt Green shot against the crossbar with the keeper beaten.
There were plenty of changes to the team as Wilder rested players who will be key in the play-offs, and also tried out others.
As well as Billy Turley taking over in goal from Ryan Clarke, Potter and San Deering, the starring subs against Mansfield, came in from the start.
James Constable was rested, while Mark Creighton and Dannie Bulman were not risked after recent strains and knocks.
The U's took the game to their opponents from the off, and had a bit of a swagger about their play, which is no bad thing, indicating their newly-regained confidence.
Jack Midson tried a clever dummy, but as well as fooling Wrexham's defenders it also fooled his teammates, with none anticipating him letting the ball run.
And when Matt Green had a sight of goal 15 yards out and from a tight angle, he still tried shot, and his low drive was pushed around his post by keeper Chris Maxwell.
Turley showed good alertness in coming quickly out of his area to head clear - and a diving header at that - when the dangerous Andy Mangan bore down on goal.
Similar to a week ago, a number of United players hit stray passes, though often it was because they were trying to be inventive in their movement and interchanges. A couple of times it was just sloppy.
Adam Chapman mixed good and bad.
It looked on one occasion as though he was too much believing the good press he was getting as he was dispossessed when trying a very fancy pass.
But he followed that later in the first half with two terrific 50-yard quarterbac-like deliveries out to Damian Batt on the right touchline.
Rhys Day had a great chance to open the scoring three minutes into the second half when he was unmarked as he met Chapman's right-wing corner. But he headed over the bar from five yards.
Frequently the ball fell to Deering in good positions just outside the box, but despite the home fans shouting 'shoot' that is not his strength from that distance and he couldn't get one on target.
There were some moments of skill in other areas, though - Potter's close control in tight situations, and one superb retrieving tackle by Jake Wright on Mangan after he had initially given the ball away.
Potter jinked his way around five opponents some 25 yards from goal before trying his luck with a right-footed drive, which flew narrowly wide.
The gate was a disappointing 4,700, the lowest league attendance of the season.
But then, on this 24th anniversary of the Milk Cup Final, many Oxford fans had their minds on other things, and some had already bought their tickets for the home leg of the play-off semi-finals as United strive to reach Wembley again.
Wrexham almost grabbed a goal following a superb 70-yard throw-out by goalkeeper Maxwell. Gareth Taylor skied his shot from the resulting right-wing cross, a good opportunity missed.
In injury-time, and in front of the home fans, Turley produced a fanastic save from Wes Baynes' powerfully-driven 20-yard free-kick, which was blasted straight through the wall.
Somehow the veteran keeper managed to divert the ball against a post and to safety, and a few minutes later, at the final whistle, the crowd were chanting his name.
Oxford Utd: Turley 7, Batt 6, Day 6, Wright 6, Sandwith 7, Chalmers 6 (Bulman 7, 63), Chapman 7, Deering 7, Potter 8*, Midson 6, M Green 7 (Woodley 89). Subs not used: Clarke, Hargreaves, Cook. Booked: Chalmers.
Wrexham: Maxwell 7, Obeng 5, Westwood 6, Assoumani 7, Brown 8, Cieslewicz 6 (Baynes 76), O'Leary 6, Taboubi 6 (Spann 89), Hunt 7 (Mitchley 89), Taylor 6, Mangan 7. Subs not used: Mike Williams, Smith. Booked: O'Leary, Hunt.
Referee: Ian Smedley (Derbyshire) 5.
Att: 4,745 (86 from Wrexham).
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