The Cape side looked set to earn all three points until substitute Geofrey Serunkuma struck in the final minute.
Celtic were buzzing early on, with Tlou Segolela in particular looking a real threat down the left wing. It was Segolela, on loan from Orlando Pirates, whose industry saw Celtic create the first chance of the game as he let fly with a 20-yard effort which Langeveldt, back in the team in place of the dropped Francis Chansa, did well to save.
Despite not showing much in attack early on, it was Santos who scored the opener in the 13th minute. The goal materialised from Erwin Isaacs’ corner-kick, which was emphatically buried into the back of the net by Eleazar Rodgers’ head.
Seven minutes later a good move from Santos resulted in Musa Otieno looking to extend the lead, but his 25-yard shot was too close to Celtic keeper Shu-aib Walters, who made a fairly routine save.
The likes of Mark Mayambela and Segolela did their best to try and get Phunya Sele Sele back into the game, but some poor option-taking in attack saw no real chances being created. However, just before the break, Mayambela should really have made it 1-1, but he sent a free header well over the bar.
Eight minutes into the second half Isaacs looked to extend Santos’ lead from a free-kick, but he sent his effort sailing over the bar. The visitors also had a couple of attempts from set-pieces, but both Mayambela and Moses Spandeel’s free-kicks failed to force Langeveldt into a save.
Segolela was presented with a clear-cut chance in the 62nd minute but, from right in front of goal, the ball skewed off his boot and flew well wide of target.
The Free Staters remained in the ascendancy for the balance of the game, but again the lack of a killer instinct in the vicinity of the Santos goal meant that Santos’ defence was never under any undue pressure.
However, that lasted until the 90th minute, when Serunkuma turned in the box before shooting goalwards. It was not the best-hit shot, but Langeveldt spilled the ball, which trickled over the line to hand Celtic a life-line in their quest to avoid relegation.