Joe Schmidt has urged his Ireland side to "grasp the moment" as they seek to follow up their maiden Test victory over the Springboks in South Africa by sealing a series win in Johannesburg on Saturday.
Ireland overcame the first-half dismissal of CJ Stander, for a dangerous tackle that concussed Pat Lambie, to secure a historic 26-20 triumph at Newlands last weekend.
Schmidt has made five changes to his team for the second Test, prompting suggestions the tourists may be seeking to keep something in reserve for the series finale in Port Elizabeth.
Ireland's head coach said: "I think that's probably an insult to the players who have come in, to be honest.
"I'm really hoping that they'll pleasantly surprise just as the players who were probably under-valued a little bit last week certainly showed their mettle.
"It's a huge challenge to those players that have come in, to try to match what the players put into the game last week."
Springboks coach Allister Coetzee, who has replaced the injured Lambie and Lood de Jager with Elton Jantjies and Pieter-Steph du Toit respectively, was highly critical of his team's efforts in their first match under his stewardship.
And Schmidt anticipates an improved home performance at Ellis Park.
"We have no doubt that South Africa will have benefited from that hit-out," he added.
"It's very difficult for someone like Allister to come in and implement a strategy in the space of maybe half a dozen trainings, so each time they play together.
"If we're waiting for PE, they'll likely be better again, so I think it's important that we don't wait, that we try and grasp the moment."