The 26-year-old former AC Milan forward is poised to sign on loan from Brazilian club Corinthians until the end of the season.
"It's not a gamble," Hiddink said.
"Coming on loan makes it possible to have a good view on him, whether he is able to adapt to the high demands of the club and the league
"He is in London
He is now in the process of bureaucratic paperwork."
Pato has been hampered by injuries in recent seasons and it is uncertain when he will first be available to Hiddink and Chelsea.
The Dutchman described the move as "a brave step" and the success or failure depends on the player.
He added: "It's up to him."
New York Red Bulls defender Matt Miazga's move is near completion, too.
"We're not rushing, but he will be one of the squad members for the future," Hiddink added.
Source : PA