Celtic would have leapfrogged AmaZulu into eighth-place had they won, and they looked destined to do just that after leading the majority of the match thanks to a first half penalty from Lennox Bacela.
But Usuthu substitute Josef Lekata netted an injury-time equaliser to salvage a 1-1 draw for his team, which keeps them in the top half at Celtic’s expense.
After a quiet opening to the match, it came to life just past the quarter-hour mark when Belux Bukasa Kasonga gave away a penalty. Bacela coolly converted the spot-kick to make it 1-0 to the home team.
Both sides created half-chances in the remainder of the first half, though neither Thabani Stemmer nor Tapuwa Kapini were called into any really significant action.
The teams had clearly struggled to tell each other apart from their similar colours in the first half as at the start of the second they re-emerged in different strips: Celtic switched to their all-white change strip, while AmaZulu went to their first choice of all-green.
Seven minutes after the restart Celtic should have doubled their advantage. Thokozani Mshengu surged forward down the right and provided a perfect cross for Phenyo Mongala, but the former Orlando Pirates winger somehow directed his header off target when it seemed easier to score.
By the 62nd minute AmaZulu had used all of their three substitutes in an effort to get back into the game, introducing Josef Lekata, Donovan Thompson and Thamsanqa Sangweni. However, they were unable to create any clear chances in regulation time with which to bring themselves on level terms.
Yet Usuthu never gave up, and in the last of three minutes of referee’s optional time they equalised, as Lekata rose highest to meet a free kick and direct a header into the back of the net, salvaging a 1-1 draw for the KwaZulu-Natal side when they seemed destined for defeat.