Motherwell came from behind to claim all three points and, with St Johnstone drawing, the victory strengthened their grip on seventh place.
Victory for the visitors would have hoisted them seven points clear of the play-off position with three games remaining but, should second-bottom Partick Thistle beat Ross County on Friday, they will be just one point ahead of them.
Dundee ought to have taken the lead inside the opening 20 seconds. Simon Murray’s deep cross was met by Craig Wighton, stealing in at the far post, but he failed to direct his effort on target. There was more bad news for the visitors when their leading marksman, Soufien Moussa, had to be replaced by A-Jay Leitch-Smith just three minutes later. Ryan Bowman came closer to breaking the deadlock with a header from Chris Cadden’s delivery which rebounded off Elliot Parish’s right-hand post; the striker nodded the rebound directly at the goalkeeper.
There was nothing Trevor Carson could do to prevent the visitors going in front, however. Caulker headed a Paul McGowan corner back across goal and Genseric Kusunga was on the spot to prod the ball home from a yard out. It was a short-lived lead, Motherwell restoring parity from a set play of their own when Charles Dunne nodded on Cadden’s corner for Bowman to divert the ball behind Parish.
Bowman was forced to leave the field after 41 minutes after Kusunga fell on top of him and, although the Angolan re-appeared for the second period, he collapsed before play began and, following an eight-minute delay, was replaced by Darren O’Dea.
His absence was notable when Frenchman Cedric Kipre rose above everyone at the far post to score with a downward header from Cadden’s free-kick. The home side enjoyed the upper hand after that, although A-Jay Leitch-Smith could have restored parity when he was released by Cammy Kerr’s perfectly-weighted through ball. Unfortunately for the striker, a poor first touch meant that the chance was lost.
Dundee piled on the pressure but Mark O’Hara blazed wildly over from another Caulker knockdown at the death. Manager Neil McCann, though, was relieved that Kusunga had recovered. “It’s not great when you see a player sit down like that,” he said.
“I went over to see him and he looked absolutely sparked. He was like a boxer; his eyes were gone, he was having chest pains and was struggling to breathe – I think as a result of the impact when he got our goal, when he took one on the chest.
“The doctor is satisfied that it isn’t anything sinister, which was my worry, but he’s lucid again and seems to be okay.”