A controversial penalty six minutes from time enabled Eastbourne Borough to stay up by the skin of their teeth.
It looked like Oxford United's makeshift side was going to break their hearts by holding them to a goalless draw in this final match of the season.
And with Gateshead scoring early and going on to beat AFC Wimbledon, the Sussex outfit knew they had to also collect all three points to avoid relegation.
There was little between the sides in a bitty game, but as the clock ticked round to 84 minutes, substitute Joe Benjamin's shot hit the arm of Mark Creighton, and a linesman flagged.
The referee wasn't going to give anything, but he had to go with his assistant's decision, even though he was 60 yards from the incident.
Up stepped former United midfielder Simon Weatherstone, and he sent Ryan Clarke the wrong way from the spot.
So Oxford ended in third place in the table, and they will play fourth-placed Rushden & Diamonds in the play-off semi-finals.
John Grant, whose loan spell from Aldershot has not been the most successful, had almost fired the U's in front moments earlier with a fine turn and sweet left-foot drive that keeper Greg Nessling pushed over his bar.
Manager Chris Wilder missed the game to spy on potential play-off opponents Rushden and Luton, but he was also serving a one-match touchline ban for being sent to the stand at Hayes & Yeading on Good Friday, so he wouldn't have been able to be in the dug-out anyway.
After the recent dry spell, the pitch was hard and bobbly, leading to a further concern that United players might pick up injuries.
Ryan Clarke took his place in goal again and the U's had three big centre halves in Rhys Day, Mark Creighton and Kevin Sandwith.
But at first it was hard to know whether it was a wingbacks system or 3-4-1-2 because Anthony Tonkin started by operating very deep rather than as a left midfielder or left wingback.
Sandwith followed up one crunching tackle, and some neat passing out of defence with two brilliant 50-yard crossfield passes to Damian Batt, though Batt failed to control the first of them.
Eastbourne had drafted in Nessling from nearby Hastings, who was also registered by them, to solve their goalkeeping crisis, but it was asking a lot of him in such a high-pressure game, as he had only previously made one first-team appearance for Borough.
The home side were not shy to shoot. Matt Crabb let fly with a left-foot effort from 20 yards, which flew narrowly wide, and Jamie Taylor sent in a low shot on the turn which wasn't far wide of Clarke's goal.
Up front for United was a new partnership of Grant and Jamie Cook, with Sam Deering in the hole behind.
Coo managed a low left-foot shot from Grant's flick-on, but it lacked the power to trouble Nessling.
And when Deering attempted a curling shot from 16 yards, he scooped it well over.
There hadn't been much goalmouth action in the first half, but it burst into life in injury time.
First Deering knocked the ball sideways for Cook ten yards out, but Cook's first touch wasn't the best.
And from that promising attack, Borough broke down the other end and Weatherstone went close with a curling shot that beat Clarke but drifted a yard beyond the far post.
Eastbourne started the second half well but Matt Crabb shot horribly wide from a good position on the right of the box.
The home side had stepped it up considerably and when Luke Rooney fired in a great shot from 25 yards, he saw it beat Clarke all ends up but hit the underside of the bar, and was then cleared.
In the second half, United brought on Adam Chapman and Simon Clist to look at their options in wide defensive positions.
But in the end, it was just a very dodgy late decision that settled the contest.
Oxford Utd: Clarke, Batt, Day (Chapman 62), Creighton, Sandwith, Tonkin (Clist 71), Deering, Chalmers, Hargreaves, Grant, Cook (M Green 85). Subs not used: Turley, M Green, Woodley.
Booked: M Green, Chapman.
Referee: Brendan Malone (Wiltshire).
Att: 2,634.
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