The Portuguese capital club have reportedly won the race for the sought-after talent, with a transfer expected to be finalised in the next few days
The 17-year-old is widely regarded as one of the hottest prospects in South America, with the Paraguayan striker having been linked with Chelsea in recent times.
Guggiari says that an agreement with Benfica has not yet been reached, but is confident that Caballero's future will be decided soon.
"At the start of this week, Mauro's transfer should be resolved," he told O JOGO. "There will certainly be contact with Benfica."
Portuguese sources claim that Benfica will spend a fee of €3 million for Caballero, who is expected to move to the Estadio da Luz only in January, when he turns 18.