Goals by Themba Zwane, Lesedi Kapinga and captain Hlompho Kekana ensured a dominant win as Sundowns advanced to the competition's semi-finals.
After an encouraging period in the first-half after striker Tshegofatso Mabsa grabbed an equaliser to make it 1-1, Sundowns retook control of the game and dominated proceedings.
Masandawana's dominant performance went a long way to solidify their status as this country's premier football club, by some distance.
After the final whistle, a disappointed Zinnbauer admitted that his side were simply outclassed by the better team.
"We didn't show enough today to convince that we deserved to win today," Zinnbauer told SuperSport TV post-match.
"In the first 10 to 15 minutes we were completely out of the game, then we grabbed a goal and maybe this served as a wake-up call.
"Sundowns were just too good, I am honest and can admit that and that they have top players on the field.
"They have been playing very well in the Champions League, have been doing well also in the PSL and we chased the game in the final minutes and that's also where they got their goals.
"But I'll say it again, our performance was not enough and the opponent were better but the score may be a bit too flattering to them."
Pirates will look to bounce back when they face Maritzburg United at Orlando Stadium on Sunday.
Kick-off is at 18:30.