Pirates beat Royal AM 2-1 courtesy of goals by Vincent Pule and Thabiso Monyane while Mokete Mogaila was on the scoresheet for Thwihli Thwahla.
Riveiro explained after the game that he was more than happy with the performance of his charges than the actual result.
"Ja well again extremely happy with the result but more than that extremely happy with the performance today," Riveiro told SuperSport TV.
"I think we did it very well in different phases, the game has different moments, both teams with different approaches. We got an advantage very soon which us very important in these type of games.
"Because the opponent needs to immediately react and play more open. It was a pity that we could not finalise the game before, with some transitions we had in the first-half and some mistakes we provoked in the pressing.
"But we did not suffer so much, we conceded one goal we could avoid in the second action but the way these guys are fighting every three days is something to put really in value. We are very proud of them."
Riveiro was asked to elaborate on the reasons behind their pressing game, which yielded them an early goal.
"It's coming also because of the surface, if you play short passes in this ground or even total passes you need to be really careful otherwise you'll pay the bill," he added.
"And it happened a couple of times, more than the goal and it's something we did very well in that sense, we avoided nervous things and situations where could suffer. Play more practical than usual, we were more a pragmatic team today but I think that's what the game was asking us to do and we did it fantastically."