Dom Sibley spent eight-and-a-half hours at the crease as he chased down his first Test century but the opener is treating his epic innings against South Africa as the culmination of a 10-year journey.

Sibley resumed on 85 on day four of the second Test in Cape Town and walked off the field as a newly-minted England centurion, with 133 not out in the tourists' 391 for eight declared.

It could yet prove a key contribution to the 24-year-old's first victory on the big stage but England will need to get eight more wickets on the final day if they are to square the series.

The Proteas have no intention of making it easy, moving to 126 for two after 56 hard-fought overs, but whatever unfolds Sibley can take pride in his efforts.

As a 15-year-old he turned out for Surrey's 2nd XI and three years later he was scoring a double century for the first team while still a student at Whitgift School. But by 2017 he was surplus to requirements at the Oval and making heavy weather of his early days at Warwickshire.

All of that and more will have played a part as he leapt to celebrate his hundred before embracing his partner Ben Stokes.

"The moment I saw the ball go for four is what I've been working towards since I was maybe 13 or 14," he said.

"You're never quite prepared for the spotlight that you'll be under – people writing about you and depicting your technique," he admitted.

"It is tough to avoid in this day and age. It didn't bother me too much but perhaps subconsciously you are thinking that you need that score for yourself and prove that you are good enough at this level.

"The first two tests I played I put myself under a lot of pressure to get that first big score. It was a case of taking the pressure off and playing the way I did in the summer for Warwickshire and just going about it the way I do, without worrying too much about what others are saying.

"It was about believing that what I do well is enough to succeed at this level."