Four days after falling on penalties to Kaizer Chiefs in the final of the MTN8, Sundowns looked set to suffer their first League defeat of the season when United skipper Ricardo Katza handed the hosts a lead inside 20 minutes, but second-half substitutes Dillon Sheppard and Monteiro combined to claim a point for the Brazilians.
Sundowns had to do without regulars Mbulelo Mabizela, Lerato Chabangu and Surprise Moriri, who had all played in the midweek MTN8 final against Kaizer Chiefs.
However, Kurt Lentjies, who may not have started had the likes of Chabangu and Moriri been available, impressed in the opening minutes with his assured and confident play in midfield. The youngster tested United goalkeeper Dennis Onyango with a stinging drive in the ninth minute and also looked set to be through on goal a short while later until Morgan Gould came across to make a fine tackle, as Sundowns dominated the early stages.
But the Brazilians soon found themselves behind, as the unmarked Katza rose highest to meet Elias Pelembe's corner kick in the 19th minute and scored the easiest of headers to put SuperSport 1-0 up. Sundowns weren't helped by goalkeeper Brian Baloyi's half-hearted attempt to come off his line and try claim the ball, only to be left in no-man's land as it bounced past him into the net.
Daine Klate almost scored a carbon-copy goal three minutes later, heading wide from another Pelembe corner. Sundowns coach Trott Moloto must have been highly concerned with his side's vulnerability at set pieces, particularly with the aerial power that Matsatsantsa had at their disposal.
But instead of another aerial barrage, Sundowns were soon threatened by the pace of Fikru Tefera, as the lanky striker powered his way down the left channel in a move that ended with strike partner Katlego Mashego directing a shot at goal on the turn, though Baloyi redeemed himself with a good save low to his right.
The Brazilians' goalkeeper was called upon to make another fine save nine minutes into the second half, punching away Klate's well-struck free kick that he would have seen late from behind the wall of defenders.
Klate was given a great chance to double his side's advantage in the 57th minute, finding himself free on the edge of the box after a great pass from Brent Carelse, but the winger blasted his shot way off target.
Sundowns left-back Sydney Plaatjies tried his luck from long range just prior to the hour mark, only for Onyango to make a comfortable save, and a few minutes later Lentjies couldn't direct his header on target from an angled free-kick.
United's Liberian forward Anthony Laffor had a fine chance to extend his side's lead mere seconds after coming on as a substitute in the 65th minute, but his sliced volley warranted no concern from Baloyi.
Matsatsantsa's were made to pay for their profligacy in the 72nd minute when substitute Dillon Sheppard played a neat one-two with Josta Dladla before a superb cross that was turned home by Monteiro, another replacement.
United were given a further headache when Onyango soon had to be stretchered off having injured himself in an attempt to keep out the goal, though they could call on the experienced Andre Arendse to take his place.
And the former Bafana Bafana 'keeper made a crucial block from Lentjies a minute into injury time to ensure his side took home a point.