Prandelli has another chance to assess some of his players as Italy prepare to face the Republic of Ireland in a friendly in London on Saturday.
FIFA's deadline for finalising 23-man squads is Monday, and Prandelli has several tough choices to make.
He said it was the most difficult part of his job, with his side facing Uruguay, England and Costa Rica in Group D at the FIFA World Cup.
"This is the hardest part of my job, as usual you've always got to talk straight, meaning that you have to say 'These are the 23 best players I could select'," Prandelli told a news conference on Friday.
"I have seven forwards and I'll have to bring only five, to the ones that should not make it, please don't consider it a failure, it's a choice I have to make in order to apply on the pitch a certain tactical idea I have in my head.
"It's going to be very tough, especially because the lads are making a lot of sacrifices, they've dreamed of playing the World Cup for so long.
"It's going to be a very emotional moment for them, difficult for all of us. It's not going to be easy announcing the list, such a definitive decision is going to be tough, no doubt about that."
Fiorentina striker Giuseppe Rossi, hampered by injuries throughout the 2013-14 season, will start against Ireland and appears set to make the final 23.
Prandelli, who signed a two-year contract extension on Tuesday, also defended himself after criticism of his wages.
"I don't want to play games here," he said.
"In the last few days people are questioning my morality, people who, let me be clear about it, have had their phone under control by the courts for behaviours less than honourable.
"And they have the gall to question my morality?"
