Competing on many fronts, Sundowns made as many as six changes to the starting line up from their last clash, with the likes of Andile Jale, Gaston Sirino, Rivaldo Coetzee and Phakamani Mahlambi being drafted into the side.
Chippa pulled an early surprise when Rhulani Manzini’s free-kick left Denis Onyango flat-footed en-route to finding the bottom corner on three minutes.
The Brazilians were nearly two down inside seconds after Thabo Rakhale skinned the defence to go one-on-one with Onyango, but the latter’s intervention staved off any threatening action.
The chances continued to fall for Chippa who left the visitors defence in tatters after Rakhale missed a sitter from a right-sided cross on 20 minutes. while Sundowns were then saved by the crossbar after Tercious Malepe was afforded space to run from midfield to get a long range shot away.
The misses came back to haunt Chippa after Phakamani Mahlambi brought down a diagonal ball from Sirino to beat Daniel Akpeyi at the near post on 32 minutes.
Mahlambi missed a good opportunity to go in front at halftime, but the former Al Ahly winger couldn’t finish off a neatly-worked move into the box.
In the second half, Sundowns made the first change when Kekana replaced Jali who struggled to keep up with the pace of the game.
Miscommunication between Themba Zwane and Mahlambi resulted in the latter’s effort cleared off the line by his teammate midway through the second stanza.
The woodwork was rattled after Mkhulise took Gaston Sirino’s through ball into his path before stinging the crossbar as Sundowns upped the pressure going in search of a winner.
On 60 minutes, Clinton Larsen opted for a double switch in Mark Mayambela and Ruzaigh Gamildien, with Rakhale and Kurt Lentjies making way.
In the closing stages, Sirino failed to make use of a good opportunity on the byline when he shot over the top from close range.
Three minutes into added time, Federic Nsabiyumva rose high to head home the winner following a corner and sent Chippa into the last 16.
Chippa: Akpeyi, Macheke, Nsabiyumva, Shitolo, R. Manzini, Malepe, Tlolane, Komane, Rakhale, Lentjies, Mbenyane.
Subs: Mzimela, Mayambela, Manzini. Makobela, Klate, Gamildien Malama.
Sundowns: Onyango, Ngcongca, Coetzee, Lebusa, Langerman, Mohomi, Jali, Mkhulise, Zwane, Mahlambi, Sirino.
Subs: Pieterse, Maboe, Madisha, Manyisa, Brockie, Kekana, Lakay.