While his team-mates enjoyed time off to play in a charity golf day hosted by a local casino, Smith was training hard to recover from the hamstring injury that put his participation in doubt.
"Juan is fine now," Springbok communications manager Chris Hewitt said on Wednesday.
"We had kept him out as a precaution, but he has come through well and he is expected to play on Saturday.
"All 30 players with us are fit and well, and we now have no injury worries."
Meanwhile, Schalk Burger joined the team as player number 31, but only to train alongside his team-mates because he "is of indeterminable value to the side on their way forward this year."
Burger will continue his rehabilitation from the knee injury which has sidelined him for the past five weeks.
His progress is being monitored on a day-to-day basis by the Springbok medical team, and they have expressed satisfaction at his ongoing recovery.
"Schalk is responding well to treatment and has started running," said Springbok team doctor Craig Roberts.
"He is an active presence at training sessions, continuing his rehab with physio Rene Lombard."
Burger will remain with the squad for the Vodacom Incoming Tours, despite his unavailability for the first two Tests against Wales in Bloemfontein and Pretoria.
"Schalk adds a lot to the team dynamic," said de Villiers. "He is unavailable for selection at the moment, but his off-field input has been substantial.
"He is also familiarising himself with our structures and line-out calls so that when he is ready to play it shouldn't take too long to get him up to speed."
Burger will be monitored closely in the weeks ahead, and no firm date has been set for his return.
There is a possibility he will be available for the Test against Italy in Cape Town on June 21, but no risks will be taken, with the primary goal for him to be fit for the Tri-Nations.