Selkirk looked like they would extend their unbeaten run to three games when they opened the scoring on 13 minutes last week.
A jinking run by Yannis Lamghari and a fine finish by Julio Tonelle set the ball rolling in this Lowland League encounter at Yarrow Park.
But Dalbeattie struck back with Lewis Sloan volleying in before the break.
The sending off of Kevin Barr, for a foul on Sloan, saw Selkirk face the next 45 minutes with 10 men – and Dalbeattie bagged three goals to finish the game.
Selkirk introduced new signing Mate Meszaros for his debut, and the Hungarian helped set up Phil Addison for a goal two minutes from time. This weekend Selkirk welcome Stirling Uni to Yarrow Park for a King Cup clash.