Stubbs and captain Temba Bavuma hit centuries to put South Africa in an impregnable position before their bowlers dismissed five Sri Lankan batsmen on the third day of the first Test at Kingsmead.
Stubbs (122) and Bavuma (113) ground down the Sri Lankan bowlers in a fourth wicket stand of 249 before South Africa declared their second innings at tea after scoring 366 for five.
Set a massive 516 to win, Sri Lanka were 103 for five at the close.
Stubbs, 24, said on SuperSport television that batting conditions were never easy during the more than five hours that he and Bavuma were together.
“I never felt I was really in, I had to stick to my game plan and be really disciplined, you couldn’t hit on the up really.”
Stubbs has been signed for $1.15-million dollars by Delhi Capitals for the next Indian Premier League season but said his six-hitting prowess was a relatively recent development.
"Through school and university I was a nudger," he said. "Since Covid I got a bit stronger and then I could really hit the ball. I had to find the balance which took some time.
"I prefer the red ball game. You can bat for long. It’s a lot more of a mental game. I’ve played very little red ball cricket so I’m always learning. But I love it and am just trying to grow as quickly as I can.”
Bavuma agreed with Stubbs that batting was not easy. “It forced you to stay in your plans,” he said.
He told journalists that reaching just his third century in 60 Tests, to go with 22 fifties, was personally satisfying. “Hundreds are a currency and there is a lot of confidence that comes from scoring a hundred.
“In terms of the (team) batting line-up as well, we are starting to reach a stage where each innings we believe someone can score a hundred.
“For me personally, from a mental point of view I am starting to find a little bit of a formula as to how I can go from scoring not just fifties and sixties but going on and putting the team in a very strong position.”
After being shot out for a record low of 42 in the first innings, the Sri Lankan batsmen again struggled against South Africa’s fast bowlers.
The experienced Dimuth Karunaratne fell early to Rabada for the second time in the match, again edging a drive at a ball bowled from around the wicket. He was caught at third slip by Stubbs for four.
Pathum Nissanka showed positive intent in scoring 23 off 31 balls before falling leg before wicket to Coetzee almost immediately after gloving a catch to wicketkeeper Kyle Verreynne off what proved to be a Rabada no-ball.
Jansen, who took seven for 13 in the first innings, followed up with the wickets of Angelo Mathews (25) and Kamindu Mendis (10) before nightwatchman Prabath Jayasuriya fell to a reflex catch at short leg off Rabada after scoring a single.
