The Buccaneers have won their last 10 games in all competitions and recorded a 1-0 victory at the Orlando Stadium on Saturday with captain Mbekezeli Mbokazi netting a superb winner with just three minutes of the match remaining.
Ouaddou's side, who are third on the Betway Premiership standings behind Mamelodi Sundowns and Sekhukhune United, will now await the completion of Sunday's last 16 encounters before discovering their quarter-final opponents.
Speaking after the game, the Bucs boss said on SuperSport: "First of all, I would like to congratulate my boys, it's not easy to play against Siwelele, it's a strong team, they show us a great character today with a good tactic. I know that these games will be won in small details and it came from our central defender, it give us the victory.
"I'm happy for the fans, my boys, it give us the opportunity to the next stage after the FIFA break and they have to be honest too and I'm very proud of them since they are playing every three days, winning, keeping clean-sheet so it's fantastic, we have to keep going."
Pirates are next in action against Saint Eloi Lupopo in a CAF Champions League Second preliminary round encounter on Friday.
"It's important for us, it confirmed the personality, character of Orlando Pirates," added Ouaddou. "This is the brand we want to show – a team that is able to score but a team that is strong as well so the danger can come from everywhere."