Celtic, playing away from home, thrashed Mamelodi Sundowns 5-0 to effectively end their title charge in their previous league match.
Returning to their Free State home, however, proved a more difficult affair as Maritzburg scored early and held onto their advantage for a hard-fought win.
With the triumph, Maritzburg moved to 33 points and leapfrogged Polokwane City into eighth spot on the log.
Celtic, meanwhile, remained in fifth spot with 37 points.
Kurt Lentjies scored the opener for the visitors in the ninth minute. Teammate Deolin Mekoa curved the ball into the area from a free kick, and Lentjies was on hand unmarked at the far post to nudge his effort home to make it 1-0 to Maritzburg with the game still in its infancy.
Celtic’s Keegan Ritchie proved a menace from setpieces as early as the 13th minute. His free kick from long range swerved towards goal at pace, but ended just centimetres over the target.
Celtic had an opportunity to draw level in the 37th minute from a free kick from 35 metres out. The ball was lofted into the box by Ritchie and Alfred Ndengane headed his attempt which Maritzburg keeper Virgil Vries gathered with an air of comfort.
