Nyasha Mushekwi struck early for The Brazilians, but the Clever Boys claimed a draw thanks to a late equaliser from 17-year-old substitute Muhammed Patel.
Sundowns dominated the opening exchanges and it was no surprise when they took an 11th-minute lead through Mushekwi, who did well to tuck away a cross from Siyabonga Ngubane.
Wits recovered from the early set-back, though just before the half-hour mark they almost found themselves two goals down when Mushekwi got on the end of a cut-back from Lebohang Mokoena, but his header was well saved by Emille Baron.
Five minutes later Downs had a strong appeal for a penalty turned down when David de Oliveira bundled Mushekwi over in the 18-yard area without getting any kind of contact on the ball, but the referee waved away the home side’s appeals.
Just before the break Wayne Sandilands was called into his first significant action, making an excellent double save to keep out successive shots from De Oliveira and Sibusiso Vilakazi.
Early in the second half it was Baron’s turn to show his excellent reflexes as he turned away a powerful header from Clayton Daniels, who had got up highest to meet a Teko Modise free-kick.
Four minutes later De Oliveira was mere inches away from bringing Wits level, hitting a thundering drive from 25 yards out which came back off the crossbar.
On 72 minutes the hosts needed another great save from Sandilands to keep themselves in the ascendancy as he parried away a curling effort from Sibusiso Vilakazi before a follow-up shot was cleared off the goal line by Method Mwanjali.
Sundowns’ inability to find a second goal came back to haunt them in the final minute of regulation time when Patel scored from close range, turning home a rebound after Sandilands could only parry Daylon Appolis’ free-kick.
Sundowns thought they had snatched the win at the death when Katlego Mphela forced the ball into the back of the net, but he was flagged offside and the ‘goal’ was scratched off.