Substitute Ness had only been on the park five minutes when he swept home in stunning style to chalk up his side’s third win in the space of just seven days.
Ness’ strike moved the resurgent Dark Blues to within three points of table-topping city rivals United, who travel to Inverness today, and level with second-top Ayr United.
Kane Hemmings had given James McPake’s men a 63rd-minute lead which was cancelled out 60 seconds later by Cameron Salkeld. But Ness, below, came to the rescue to ensure that Dundee head into the eagerly-awaited derby high in confidence as they seek revenge for August’s 6-2 hammering at Tannadice.
“It was a great result for us and it sets us up well for what lies ahead next week,” said McPake.
Dundee had the best of the first half but found David Hopkin’s side a tough nut to crack as they sat deep in defence.
However, they took a deserved lead in 63 minutes. A short corner gave Graham Dorrans space to pick out Hemmings with an inch-perfect cross into the box, and the striker glanced a glorious header past Sam Ramsbottom.
But their lead was short-lived. A minute later, Salkeld made it 1-1 with a cute back-post finish from Robbie Muirhead’s cross as he ghosted in to score.
The hosts, though, regained their lead with ten minutes left when Dorrans dinked a pass to Ness and the substitute curled an unstoppable left-foot shot high into the net.