Nuno Santos (17', 80') scored both goals either side of an unfortunate own-goal credited to Ronwen Williams after 19 minutes.
The result sees Sundowns lift the Intercontinental Cup and advance to the next round of games, labelled the Challenger Cup to face the winner of the Derby of the Americas.
Speaking after the game, Pusic felt his side were in control of the tie but failed to bury their opportunities.
"We knew they are a very good team and a very long period together, good playing team, and they are good in ball possession as well – so they showed that as well, one more time,” Pusic said on iDiski Times.
"I said we controlled things without conceding big chances, until the last 20 minutes of the second half, and I think we used their weaknesses in a good way – only we didn’t score a goal in that moment."
The coach also praised Sundowns for their performance, addinf: "We knew they are a good team, they have been playing for a long period together, they are in the national team for a long time together and they have a lot of automatism.
“They are fit team as well. Alwaysa tough opponent to face, but like I said – if we took our chances in our good moments, it could have been a very different game for them.”
