Despite a run of three league wins in the space of just six days – beating Golden Arrows, SuperSport United and Orlando Pirates by large margins, The Brazilians came unstuck in a surprise 1-0 loss to TS Galaxy at Mbombela Stadium on Tuesday evening.
Cardoso, who had not tasted league defeat since his arrival in December, conceded they are feeling the effects of their congested fixture schedule as Sundowns play catch up.
"In the first half we had enough energy to control the game, and we had to deal with their counter-attacks that are always difficult because they are quite aggressive on the counters," said Cardoso.
"But we coped with it and we had control of the match, and when we analysed at the end of the first half, emotionally it was a difficult moment because we were expecting to be winning at half-time.
"During the second half it was clear that the energy, we were with very low batteries, it was very difficult despite the intention to try and do things, the head was not easy to make good decisions – very high levels of fatigue, for sure.
"We tried to change the players we could in order to give help to the team, we changed our strategic approach and the positions on the pitch, but a lot of players were defending very aggressively and we could not overcome their defensive system."
The Portuguese tactician wants to quickly move on from the defeat, while further admitting a lesson has been learnt in as far as trying to maintain a certain level amid a 72-hour turnaround between fixtures.
"There's only one thing to do, it's look forward, get up, rest and recover. We were not the best in the world after the last match, and we are of course not in the opposite position now," he added.
"We just clearly understand that it's absolutely impossible to have a schedule like this and play the fourth match in a row every 72 hours, so I think we made a very big mistake [thinking] we don't need to makes changes for a game in 72 hours.
"Eventually it was important to put in some more fresh players to play, but we tried our best."