Although the hosts were still in a celebratory mood after their Telkom Knockout final win over Kaizer Chiefs on Wednesday night, they started on a low, losing the ball easily.
It was Pirates who threatened first through Menzi Masuku as he received a pass from Kermit Erasmus but the South African under-23 star saw his shot going over the bar.
Despite efforts to break the deadlock, the score remained 0-0 after 10 minutes of action after Khama Billiat hit the side of the net as he tried to beat Siyabonga Mpontshane on his near post.
However, after five more minutes, Sundowns scored when Billiat received a wonderful pass from Keagan Dolly — he made a good run down the left flank and beat Rooi Mahamutsa before laying it up for Castro to finish.
After 30 minutes of action, Pirates looked disjointed and Pitso Mosimane’s men had a good chance to double their lead when Asavela Mbekile turned defence into attack, but his delayed pass to Billiat couldn’t go through as it was intercepted by Ayanda Gcaba.
In the dying stages of the first half, Pirates pushed forward searching for a goal but Thamsanqa Gabuza’s attempt was way off target, and a few minutes later Menzi Masuku’s shot went straight to Denis Onyango.
It was 1-0 at half time and the second stanza saw the Brazilians coming back guns blazing, with Dolly taking a good shot, only to see it going over the target.
In the 64th minute, the combination between Billiat and Castro paid dividends as the Zimbabwean winger broke free and converted in the box, beating Mpontshane on his far corner.
As Sundowns continued to pile pressure on their visitors, defender Wayne Arendse found himself unmarked in the box, but he lacked composure as his shot sailed over Mpontshane’s goals.
With 10 minutes remaining, Billiat continued with his fine form and made a great run. Mpontshane though read the situation perfectly and the former Platinum Stars man pulled off a great save. In an aim to respond, Mpho Makola saw his shot going straight to Onyango.
In the dying minutes, Pirates failed to get something out of the match, allowing Sundowns to move to the top of the Absa Premiership log standings with 26 points and demote Bidvest Wits to the second spot on goal difference.