England face an anxious wait over the fitness of hooker Dylan Hartley and flyhalf Owen Farrell, who are struggling with back injuries ahead of this year's Autumn internationals.
England, unbeaten since head coach Eddie Jones took charge after last year's World Cup, host South Africa, Fiji, Argentina and Australia in November and December.
Hartley, who captained England to a first Six Nations grand slam in 13 years in March, could return to action in the coming weeks, according to Northampton Saints' director of rugby Jim Mallinder.
"We are hoping he'll return in the next couple of weeks but I don't want to set a date. What we don't want is to play him for 40 minutes and him then to be out for another two weeks," Mallinder told reporters.
"We want to get it sorted properly and hopefully then will not affect him for the rest of the season."
Saracens director of rugby Mark McCall did not put a time frame on Farrell's injury, which he picked up during the pre-season. The 25-year-old Farrell has 43 caps for the country.
"It is a back injury but it is not one where the physios are able to tell you he will be back by this or that point. It's frustrating for him, it's frustrating for us but he can't play until he is ready," McCall said.
(Reporting by Ian Rodricks in Bengaluru; Editing by John O'Brien)