Moeen Ali and Stuart Broad have ensured that England continue their dominance over South Africa after an all-round performance by the duo has pushed the visitors on the backfoot on Day of first Test on Friday.
Earlier the Proteas dismissed England for 458 with all the wickets being shared by the three fronline seamers and De Kock taking four catches.
But, as he chiselled run after run, Cook performed the effective task of nudging England closer to victory in the Investec First Test.
His first fifty back in the ranks was a stodgy, obdurate affair - exactly the sort of innings he has been churning out for more than a decade.
Nineteen wickets fell on Sunday, with the surface offering variable bounce as well as plenty of turn.
South Africa are already without star players AB de Villiers (rest, or possible retirement) and Dale Steyn (shoulder injury) and could ill afford to lose Philander as well. Philander, in particular, bowled with enormous control and took the two crucial early wickets of Alastair Cook and Keaton Jennings. He only had 7 when trying to hit Maharaj down the ground, only for Vernon Philander, who was fit to bowl after injuring his hand batting on the third day, to drop a simple catch at long-off. Captain Faf Du Plessis, who missed this match to attend the birth of his first child, should return.
"Throughout the whole game I think everyone contributed at some point and I think that's a really pleasing sign that the whole team has played a big part in this win".
Cook, in his first Test since resigning the captaincy had added just 10 runs to his score when he drove uppishly at fast bowler Morne Morkel and was well caught in the covers by Temba Bavuma.
That will leave them four and a half sessions and the option of two new balls to take the ten wickets.
Root and Cook know there is no rush - the dashing blades of Root himself, Jonny Bairstow, Ben Stokes and Moeen Ali can accelerate the scoring tomorrow.
Rabada condemned Dawson to a pair for the match by bowling him with a full toss that left middle stump lying metres away from the wicket.
Morkel and Philander both bowled in the opening 10 overs of the day but it was Rabada who signalled that the end of the innings was in sight when he also claimed two wickets in three balls, one of them being Moeen for 87 (147 balls, 8 fours and a six). When Bairstow was stumped for 51 off Maharaj, South Africa's prospects of winning had all but faded.
In reply, Broad soon removed debutant Heino Kuhn, and struck again after Moeen's quick double to reduce the tourists to 104-4.
South Africa continued to struggle in the post tea session as Liam Dawson (2-34) trapped Hashim Amla (11) LBW.
Root added: "The thing I was anxious about most was that I tossed the coin right - I brought a quid out with me but [the officials] had three already so I had to use one of those!" He tried to heave Moeen through the leg side but was bowled.