Saracens hooker Schalk Brits says South Africa could target England's lineout but will still face an uphill battle at Twickenham on November 12.
Brits, whose team-mates at Saracens include injured England locks Maro Itoje and George Kruis, believes the duo's absence could cost England.
"The lineouts could be a weakness for them which we can try and exploit. George usually take the lead there," said Brits.
England are also sweating on the fitness of Courtney Lawes which means it's still unclear who Joe Launchbury's second row partner will be. England coach Eddie Jones is already without James Haskell, Jack Clifford, Sam Jones and Mike Williams.
Despite all the injuries, Brits still believes England will pose a big challenge.
"I think the current England side is a more complete team compared to the one who won the 2003 World Cup. They are young, but a very special group. Players like Owen Farrell, Billy Vunipola and Dan Cole are big assets. They grew together and struggled in last year's World Cup, but they are better for it after that experience.
"Eddie has given them structure and confidence."
Brits feels England are the best team in the world bar New Zealand, "but they have a mental challenge on Saturday because they haven't beaten us in the last 10 years. That counts in our favour."
However, the Boks need to get past the Barbarians first and Brits feels it's important they build momentum in that game for the Test at Twickenham.
"The confidence in the Bok squad is probably low and that's why it's important to build momentum," he added.
"It's going to be a tough tour. England will be difficult to beat, especially with the momentum they have. After that it's Italy before another tough Test against Wales."