The Brazilians resume domestic action after the FIFA break on Friday, with the Premier Soccer League squeezing their cup fixture, which was postponed due to a stadium booking mishap on 9 March, in before their CAF Champions League quarter-final against Esperance next Tuesday.
Onyango admitted the timing is not ideal, given several key players were away on international duty over the past 10 days, with preparations having been hampered for the must-win tie at Lucas Moripe Stadium.
"Preparations going into the Nedbank Cup are going well. Of course we would have loved to play [the match] a couple of weeks back – the game was postponed and we were in camp, slept in a hotel and you know how it is when we prepare for a game," said Onyango.
"But we're looking forward to the game once again, even though some guys were with the national team and they will come in and join us for just a few days.
"But we have no choice, we have to play because we have a lot of games, in terms of the league, Champions League, and, of course, the Nedbank Cup."
The former Uganda international assured they will all be up for the encounter, which will also give them some mileage ahead of next week's first leg tie against the Tunisians.
"The guys are looking forward to it and everyone given the opportunity has to give his best because we are all here to play," he added.
"I think the game on Friday will give us one more game before we play the Champions League game against Esperance on Tuesday. But so far so good and we're looking forward to it."