And while they will nearly certainly secure the series win either with victory or stalemate here, they will enter the series against West Indies looking nervously at their Ashes plans.
The opener will emerge from the South Africa series with an average of 15.87 in his eight knocks and that is taking into account some huge slices of luck.
South Africa, 43 for three at lunch, saw Hashim Amla (83) and captain Faf du Plessis (61) put on 123 for the fourth wicket after James Anderson, bowling from the newly-named James Anderson End on his Lancashire home ground, and Stuart Broad had made early inroads.
"The great thing for their team is they've nearly got an extra player every time they can pick from", said South Africa captain Du Plessis in the post-match presentation.
However, the England board confirmed that they have not been approached by South Africa until now and any decision will only be taken after the conclusion of the ongoing Test series between the two teams.
Dawid Malan fared no better as he was dismissed by Keshav Maharaj for six runs, but captain Joe Root and Ben Stokes stemmed the bleeding with a 57-run partnership before Root was clean bowled by Olivier for 49. They played very well, they're two world class players.
Add to that his impressive haul of 252 runs - including his onslaught on the third evening of this match (he eventually finished 75 not out as England were bowled out for 243 in the space of 17 more deliveries this morning) - and Moeen, second spinner or not, has marched unequivocally into the annals of the game's most telling allrounders. Before Ali's entrance, England was in some trouble at 129-5 and then 153-7.
By contrast to the struggles and anxieties of the top-order, England No.8 Moeen Ali made another happy-go-lucky half-century.
"I just went with the flow".
England remain strong favourites to win the fourth Test against South Africa after Moeen Ali's late strokeplay arrested their second-innings slide.
With that, the Proteas were all but done.
"A lot of teams could fall into that situation", he said of having one foot on the plane.
"The quality of the English bowling attacking was superb this series, they were relentless".
"I had a few hacks early on that I got away with but I felt the situation of the game needed a little impetus, a few shots".
Root was also in search of a victory in his first Test series as England skipper.
Match-winner Moeen Ali is congratulated by Englands head coach Trevor Bayliss (Picture: Anthony Devlin/PA Wire).
Olivier then proceeded to take out Stokes and wicketkeeper Jonny Bairstow in quick succession for 23 and 10 runs respectively.