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."

No. 8 Billy Vunipola looks set to miss another weekend of action as he continues his recovery from the fractured arm sustained against the Ospreys in January.

Saracens face London Irish on Sunday but the final game of the regular season against Gloucester six days later appears a more accurate date for his comeback.

"Billy is close but he hasn't had a lot of field sessions. Today [Wednesday] was probably the toughest session he has done so we'll see how he reacts," McCall said. "It's almost 16 weeks that he has been out for and he has had one and a bit field sessions, which is not very much.

"We don't want to put him in a rugby match without having done too much rugby. People should manage their expectations. He doesn't really have a bank of games behind him this year."