Khuliso Mudau opened the scoring at the Al-Hilal Stadium on 67 minutes but the home team fired back with a 72 minute equaliser from Mohamed Abdelrahman.
It could have ended in defeat for the Brazilians but Ather El Tahir had a 92nd minute penalty saved.
Both sides were full of energy at the start of the tie but it was Sundowns with the first real opportunity as Teboho Mokoena fired just past the Al Hilal goal with seven minutes played.
The home side were also eager to make an early impact and Makabi Lilepo saw his long-range shot well kept out by Ronwen Williams.
Fabrice Ngoma then saw his header plucked out of the air after connecting to a Ibrahim Imoro cross.
Cassius Mailula's 13th minute shot was blocked, while Lilepo was again denied by Williams as the action swung from end to end.
Lilepo continued to be a threat for the home team, alongside Ibrahim Imoro, who was unlucky not to make more of his effort on 28 minutes, while the half ended with Mudau firing just off target and Teboho Mokoena trying his luck with a couple of late half chances.
Sundowns midfielder Marcelo Allende tried to make a fast start to the second half but failed to beat Ali Abdallah Abu-Eshrein in the Al-Hilal goal.
Themba Zwane then fired wide with the keeper stranded, as Mudau was off target from a tight angle following some neat inter-passing with Zwane.
Sundowns were the more dominant attacking side and Aubrey Modiba and Mokoena both came close until Mudau broke the deadlock with just over 20 minutes of the match remaining with an easy finish from the edge of the small box.
But no sooner had Sundowns finished celebrating then they found themselves back on level terms, as Abdelrahman popped up inside the area to slot home.
Abuaagla Abdalla may have given the home team the lead moments later but his shot was blocked, while Lilepo wasn't far off with his attempt following a break away on 82 minutes.
Sundowns substitute Sphelele Mkhulise then wasted a good chance for all three points, but not more so than Ather El Tahir, who saw his 92nd minute penalty saved after Brian Onyango brought down Yasir Mozamil in the box.
The Brazilians had already qualified for the quarter-finals despite the result but ended the afternoon on top of the standings with 11 points from five games, and one match left to play - and Al Hilal in second on 10 points.