Mothiba was surprisingly named in the starting XI as Sundowns made several changes for Sunday's first-leg clash at Lucas Masterpieces Moripe Stadium, with Brayan Leon, Iqraam Rayners, Ronwen Williams and Themba Zwane among those left out.
The decision ultimately failed to pay off as Sundowns suffered a 1-0 defeat, with Junior Dion scoring in the first half to give Arrows a crucial advantage ahead of the return leg next weekend.
Mothiba had an opportunity to justify Cardoso's selection when he found himself with only the goalkeeper to beat, but the experienced forward was unable to convert the chance. He was subsequently replaced by Leon at half-time.
Despite the missed opportunity and Mothiba's limited impact since joining Sundowns in March 2025, Cardoso believes the striker deserved his chance after impressing on the training ground.
"Lebo has shown character; he made good training matches and scored in them. So, he gave us all the energy," Cardoso explained after the defeat.
The Portuguese coach also stressed that Mothiba has not been Sundowns' first-choice striker, with Leon and Rayners generally ahead of him in the pecking order.
"Lebo has not been the first option in the striking position; Brayan, together with Rayners, have been the first option," he said.
Cardoso's decision was also influenced by the demands placed on his squad, particularly Leon, who had been involved in a demanding run of matches after an inconsistent pre-season.
The Sundowns coach revealed that Leon was still feeling the effects of the recent schedule, making rotation necessary as the club competes on multiple fronts.
"It was absolutely normal that we had to rotate the players, and Brayan is too tired," Cardoso said.
"I thought he was still tired; he's not as fresh as we would like to have him, so the rotation has to do with that."
Cardoso admitted that consistency can be difficult for players who are not regularly involved in matches, but he remains keen to give Mothiba opportunities to regain his rhythm.
The coach pointed to Lucas Ribeiro's struggles in front of goal during a previous spell at Sundowns as an example of why patience can eventually be rewarded.
"I remember last year or two years ago when Lucas Ribeiro was in a period of not scoring goals; you [the media] were always asking why he didn't score. And I said, one day the goals will come, and it happened," Cardoso added.
Mothiba's missed opportunity against Arrows will inevitably raise questions about his role going forward, but Cardoso's comments suggest the striker remains part of his plans.
Sundowns will now have to overturn a 1-0 deficit in the second leg if they are to keep their hopes of reaching another MTN8 final alive.
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The league action continues this Tuesday with three fixtures pitting all the top-flight teams that are currently placed between position ten and 16 of the table.
