Quinton de Kock sensationally retired from Test cricket following South Africa's defeat to India at Centurion.
Keeper-batter De Kock confirmed his decision just hours after the tourists prevailed by 113 runs at the SuperSport Park Stadium, citing the need to spend more time with his family.
De Kock, 29, was already set to miss the remainder of the series anyway as him and wife Sasha are expecting their first child in the coming days - but the sudden announcement would undoubtedly have shocked selectors.
"This is not a decision that I have come to very easily," he said, in a statement issued by Cricket South Africa.
"I have taken a lot of time to think about what my future looks like and what needs to take priority in my life now that Sasha and I are about to welcome our first child into this world and look to grow our family beyond that.
"My family is everything to me and I want to have the time and space to be able to be with them during this new and exciting chapter of our lives. "
De Kock played 53 Tests for The Proteas, scoring more than 3000 runs and notching 225 dismissals.
He has however, pledged to continue to play white-ball cricket for his country, despite courting controversy at the T20 World Cup this year by refusing to take the knee before his country's game with the West Indies.
"I love Test cricket and I love representing my country and all that it comes with. I've enjoyed the ups and the downs, the celebrations and even the disappointments, but now I've found something that I love even more," he continued.
"This is not the end of my career as a Protea, I'm fully committed to white ball cricket and representing my country to the best of my ability for the foreseeable future.
"All the best to my teammates for the remainder of this Test series against India. See you in the ODIs and T20s."
De Kock scored 34 and 21 with the bat during his side's recent defeat, but the hosts left themselves to do much to after being bowled out for 197 in their first innings, responding to India's 330.
India were 174 out second time around, before South Africa were dismissed for 191.
The second Test starts in Johannesburg on January 3.
