Croatia beat holders Spain to win Group D and their reward is a tough game against a Portuguese side that struggled to third place in Group F despite having three-times world player of the year Ronaldo in their ranks.
"Ronaldo is their main player, so what we have to do tomorrow is not to allow him to show how strong he is, we have to limit him," Cacic told a news conference on Friday.
The 62-year-old is not reading too much into Portugal's performance in the group stage.
"Their third place was not representative of the way they played. They had three draws but they were much better than that, they were really close to winning," he said.
Portugal coach Fernando Santos dismissed talk of his side being a one-man side.
"Without a team, there are no great players. Individual talent may win a match here or there, but great tournaments are won by great teams," he said.
"It's normal, they will try to cancel him out. Sometimes the Portuguese try to downplay him, say he's not scoring, he's playing poorly.
"I'm sure my counterpart has prepared his team to play Portugal and all the positive things that Portugal has, be they collective or individual."
Dead-ball specialist Ronaldo has not had much success from set pieces at Euro 2016, even missing a late penalty against Austria, but Santos has no intention of handing those duties to anyone else.
"Any team in football has alternatives, a plan A and a plan B, but that's not the issue. A player can fail to score or fail to take free kicks or fail to take corners - are you going to change everything and hope for a miracle?,"
Croatia mid fielder Milan Badejl told reporters his side can break their duck against a Portuguese team that is the only side in the last 16 not to have a victory at Euro 2016 under their belt.
"We will try to score tomorrow. That's the only way to win these matches," he told reporters.
Badelj warned his team about under-estimating the Portuguese and being blinded by Ronaldo's star quality.
"Ronaldo is a great player, everyone knows every thing about him. It's not only Ronaldo, they have other great players that can be decisive tomorrow," he said.
(Editing by Ed Osmond)
