England captain Joe Root was encouraged by a series win in South Africa that saw a host of young players make key contributions.
Mark Wood took four wickets in the second innings as England defeated South Africa to seal the series with a day to spare.
South Africa will need to complete a world-record run chase to avoid defeat in the fourth Test with England.
In search of a 3-1 series win, England surpassed 500,000 Test runs but South Africa fought back on day one of the fourth Test.
Should England overcome South Africa in the final Test, it would mark Joe Root's proudest achievement as captain.
England moved into a 2-1 series lead over South Africa and Joe Root saluted the contribution of their young players.
Keshav Maharaj belatedly delayed England with some big hitting, but South Africa were beaten by an innings and 53 runs at St George's Park.
England captain Joe Root took four wickets, and fast bowler Mark Wood could only admire as the part-time off-spinner tormented South Africa.
Captain Joe Root is better known for his batting, but his bowling masterclass left England four wickets from victory in the third Test.
When is a declaration not a declaration? England answered the question on Friday after the decision to give Mark Wood out was overturned.