Eddie Jones indicated after the NatWest 6 Nations that he might rest some of those players who featured for the British and Irish Lions against New Zealand last summer with the 2019 World Cup in mind.
Farrell was among those most likely to be given a break - Maro Itoje, Mako Vunipola and Jamie George were also heavily involved - but the rising number of injuries headlined by Dylan Hartley's absence may have forced a revision of any plans.
The withdrawal of Hartley through concussion has a knock-on effect for Farrell, the Saracens fly-half who is the most likely candidate to take his place at the helm over three Tests against the Springboks.
"It's up to England whether Owen goes but I'm certain he will go. I haven't heard anything to the contrary and I'm sure he wants to go as well," McCall said.
"He would be a brilliant captain. He is ready to do that job and has the respect of everybody.
"He has a fantastic rugby mind but he is also brilliant at getting the best out of his team-mates. Both of those things combined make him an ideal captain.
"I thought Eddie was very good last autumn. He rested Maro and he rested Owen a lot so I am sure he doesn't want to rest Owen too much because he only played in one Test match in November. I am pretty certain he will go.
"The players feel good. They have had some time off and are feeling good and excited about the rest of the season.
"We have got a brilliant performance team here who look at match and training loads and none of the international players are anywhere near the top limits."