Springbok assistant coach Mzwandile Stick says the return of Siya Kolisi, Eben Etzebeth and Sacha Feinberg-Mngomezulu has given the squad a significant lift ahead of Saturday's Rugby Championship Test against Argentina in Buenos Aires, but insists the Boks will not underestimate a Los Pumas side missing several European-based players.

Stick is unconcerned about the fitness of the returning trio, noting that most have remained embedded in the Springbok environment throughout their rehabilitation. "The only guys that joined us now, probably in the past two weeks, were Sacha and Krappie [Morne van den Berg]. Otherwise, the rest of the guys have also been helping the youngsters," he said.

Etzebeth's conditioning drew particular praise. "He doesn't get unfit. We know he came with the concussion stuff that he had, but when it comes to fitness, he's always super fit. He looks after himself and he's a very professional player."

Kolisi was present throughout the June conditioning camp despite his hamstring complaint. "He was just unlucky with the hamstring before one of the games that we were supposed to play, where it was a bit stiff," Stick said. "When it comes to conditioning with them, I don't think it's something we're worried about."

Feinberg-Mngomezulu has made an immediate impression since rejoining the group. "It feels like he never even left the way he's training, the way he brings massive energy to our squad," Stick said.

The Boks arrive in Buenos Aires on an 11-Test winning streak and having won 11 of their last 12 meetings with Argentina, including the last three in a row. Stick is not buying the narrative that Argentina's reshuffled squad diminishes the threat, pointing to the continued presence of Santiago Carreras, Rodrigo Isgró and captain Pablo Matera.

"Those players that are playing for Argentina tomorrow, they deserve their opportunity. We can't always rely on the same 23," he said. "They are a very, very dangerous side. We'll never look down on anyone, and we have to make sure that we prepare very well."

Stick reiterated that South Africa's preparation standards do not shift based on the opposition. "We always prepare the same way, even if you're playing against Australia or Georgia or New Zealand."