Ben Morgan insists England must employ a mixture of brain and brawn to subdue the South African onslaught coming at Twickenham on Saturday.

The Springboks have been described as "the big green machine" by Mike Catt, while prop Joe Marler assessed the challenge awaiting in the second QBE International by stating "their DNA is run hard and if that doesn't work then run harder".

Morgan insists England have to be ready to put their bodies on the line against the Rugby Championship runners-up, but warns muscle alone will not be enough to underpin a first victory of the autumn.

"We know South Africa are a big, physical team who like to use route one, so we have to use our smarts to move them around and create mismatches," the Gloucester number eight said.

"We want to get South Africa running around the field chasing us. If we can do that and take our opportunities, we'll come out on top.

"If we carry into narrow channels then that's exactly what they'll want. They'll line us up from 10 metres away and come charging at us. But if we can shift the point of attack, it can make the world of difference.

"Not only does it give you the one-on-one carries that everyone wants, but it means the defence is always moving around. If you hit them tight then they don't really move.

"But you can't get away from the fact you have to carry hard too. You won't always be able to put those passes in, you have to front up and go through the line.

"Taking big hits takes it out of you, but we're advanced enough as a team to move around and cope with that sort of stuff.

"There are quite a few Premiership matches that have ended in a slogging match, so we've gone all though that type of game. We know what we're up against this weekend."

Morgan's first exposure to the Springboks was the 2012 summer tour when England were swept aside in the first two Tests before recovering to earn a 14-14 draw in Port Elizabeth.

The 25-year-old has now amassed 24 caps and he can see the progress made since the first trip abroad of Stuart Lancaster's reign.

"For many of us that was our first tour and it was a real learning curve. I was very green back then and I've come a long way since," Morgan said.

"I'm a lot more experienced and have learnt a lot of lessons through winning and losing. There were also the experience of going through that difficult patch with Gloucester last year.

"I'm definitely more rounded and I know what I have to do now. I'm better defensively, which has changed with experience."

Morgan is likely to continue in his role as number eight reinforcement to Billy Vunipola when Lancaster names his starting XV on Thursday morning.

Vunipola faded in the 24-21 defeat by New Zealand, but, while there are concerns over his fitness at international level, the 22-year-old looks set to profit from Lancaster's desire to give the same 23 another chance.

"Obviously I want to start every game. I don't want to be a bench player, but Billy's been playing well and if I can make an impact coming off the bench then I want to do that," Morgan said.

"If you start you walk on to the pitch with the intention of playing the 80 minutes, but that doesn't mean you leave anything in the tank. Basically you go out there and empty the tank.

"With the likes of myself and Billy, it's good to know someone else can step off the bench and give as much as they can."

Semesa Rokoduguni has been ruled out with a thigh problem, so Marland Yarde has been drafted into the squad as wing cover and is competing with Anthony Watson to start in the number 14 jersey.

An injury doubt hangs over flanker Tom Wood, who England say is suffering from general soreness after the All Blacks game, so James Haskell is on standby as his replacement.