Ronaldo has been whistled by some home supporters at Real's Bernabeu stadium since a poor performance in last month's La Liga 'Clasico' against arch rivals Barca.
The former Manchester United player reacted by refusing to celebrate his goal in a 5-1 win against Granada and makes his first appearance in front of Real fans since then in Wednesday's quarter-final first leg.
At a news conference on Tuesday, a cantankerous Mourinho said Ronaldo's performance in Saturday's 2-1 win at Real Mallorca had been his best of the campaign despite the fact that he had not added to his 21 league goals.
"He worked like an animal and did exactly what the team needed," Mourinho said.
"He doesn't need to score or be man of the match every time. I told him nobody can touch him after the way he worked in the second half.
"When the team wins everyone is responsible and when they lose everyone is responsible for that too. Simple."
Mourinho has managed only one win over Barca in eight attempts since taking the Real job at the end of the 2009-10 season, when Ronaldo nodded an extra-time winner in a 1-0 triumph in last season's Cupa final.
The last time the two teams played each other over two legs in the Copa, in the 1996-97 campaign, the former Internazionale and Chelsea manager was assistant coach at Barca and the Catalan club went through 4-3 on aggregate.
Mourinho refused to give any details about his tactics for Wednesday's game, saying that whatever he decided would no doubt be criticised in the Spanish media.
Angel di Maria, who has not played since injuring himself in the final training session of 2011, will be included in the squad and a decision will be made on his fitness on Wednesday.
"The (Spanish) league is the priority," Mourinho added. "But tomorrow is also a great match and you want to do the best possible and use all the players if they are available."