A first-half penalty by Mabhuti Khenyeza and a second-half strike by substitute Ryan Chapman earned Arrows their second win of the campaign. The former champions could only manage a goal by substitute Themba Zwane shortly after half-time.
Arrows were awarded a penalty in the fifth minute after Sundowns goalkeeper Denis Onyango tripped Khenyeza inside of the penalty area.
Onyango found himself all at sea after a mix up with defender Soumahoro Bangaly, and made contact with Khenyeza as the striker went past him. Khenyeza then dusted himself off and coolly slotted home the resulting spot kick.
Sundowns were stung into action by the goal, and five minutes later had a great chance to equalise when Khama Billiat found himself unmarked in the penalty area. However, his header was deflected onto the woodwork by Arrows goalkeeper Philani Zikalala.
The first half was quite an ill-tempered affair, with the referee Victor Gomes dishing out six yellow cards. Two of those belonged to Sundowns star Bongani Zungu, who then earned a red card for a second bookable offence after a foul on Rodney Ramagalela in the 17th minute.
But even with 10 men on the park Sundowns were the dominant side in the first stanza and managed to fire off nine shots at goal.
Left-footed wizard Keagan Dolly came closest with a free kick in the 22nd minute, after Nkanyiso Mngwengwe fouled Sundowns left back Tebogo Langerman just outside the area.
The Brazilians finally drew level just after halftime following some lovely interplay on the edge of the Arrows area by Dolly and Teko Modise. The ball then fell to Billiat on the left side of the area and he set up substitute Zwane to level matters.
But it was always going to be difficult for Sundowns to cope with a man down in the hot conditions. And Arrows made them pay in the 70th minute when Deon Hotto set up Ryan Chapman to slot home the winner.
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