Oxford City clinched victory over Buxton in the 94th minute in a 2-1 win at The MGroup Stadium.
The Hoops almost took an early lead when Josh Parker was found inside the area, but his effort was straight at Joe Young and was eventually cleared away.
On his debut, Tristan Gill launched a long throw into the box which picked out Kieran Burton, whose header drifted narrowly over the bar.
Connor Douglas was next to test the defence for the visitors, meeting the ball at the back post but sending his shot wide.
Oxford City’s captain Josh Ashby responded at the other end with a low free kick that forced Young into a smart diving save.
The shot stopper was called into action again in the 25th minute, this time denying Zac McEachran with another strong stop.
With this pressure, the home side did take the lead as Ewan Clark raced through on goal and lifted the ball over the onrushing Young.
Sammy Robinson was then forced off through injury, with Oliver Greaves introduced in his place for The Bucks.
Searching for the equaliser, Brennan was unable quite to pick out Adriel Walker in the area as his cross just evaded the forward.
The last chance of the half fell to the hosts, with DJ Campton-Sturridge firing a shot wide of the target.
At the break, Tai Sodje made his return from injury, coming off the bench to replace Walker.
He almost made an immediate impact when Will Trueman slipped the striker through on goal, but his near-post effort was saved and pushed behind.
Moments later, Sodje struck the post from close range after a slick passing move from The Bucks.
Ten minutes later, Oli Greaves tried his luck from the edge of the box, though his effort was comfortably gathered by the Oxford goalkeeper.
A golden opportunity fell to substitute Ryan McLean in the 77th minute as he raced through on goal, but Darnell Johnson showed great recovery pace to block the shot.
In added time, Buxton thought they had earned a point when Brennan whipped a free kick into the area and found George Ward, whose header continued his goalscoring run to make it 1-1.
But with Buxton believing they had salvaged a draw, Oxford City struck in the fourth minute of stoppage time as Johnson rose highest to head home and secure a dramatic late winner at The MGroup stadium.
