Sue Smith's charge held Eduard by three-quarters of a length to take the honours in the Grade Two race, with Red Brick 21 lengths behind in third.
The 16-1 winner was out on his feet at the end, but made a quick recovery. "He was fine quite quickly afterwards, we just loosened his girth off, got a bucket of water on him and he's grand now," Smith said.
"He's a front-running, keen little horse and he had a fair bit of weight on him today, plus the ground is just a little bit tacky out there, I would imagine."
The other Grade Two heat on the card, the totepool Mobile Text Tote To 89660 Premier Chase, also produced a surprise as Always Right (20-1) touched off Garleton.
Things had not gone smoothly for Always Right since he won at the track 15 months earlier, but John Wade's 11-year-old showed he was not finished with a gutsy display.
Ballabriggs, running in this race for the third successive year ahead of another crack at the John Smith's Grand National, which he won in 2011, was a tired third 10 lengths away.
Wade said of Always Right: "He's won here four times and been second once in five runs – I'm absolutely over the moon. He's come back to how he was. We are looking at maybe the Scottish National. He's been third there before."
The 4-5 favourite Harry Topper threw his rider Timmy Murphy when blundering the ninth fence.