AB de Villiers is unsure whether he will take over as South Africa’s test captain following Graeme Smith’s unexpected retirement.

Smith made his shock call to step away from international cricket after day three of the decisive third test against Australia in Cape Town.

As Smith’s vice-captain and the Proteas’ one-day captain, De Villiers is the most obvious choice to take charge of the world’s top-ranked side.

But he told Cricket Australia’s TV channel: “I’m not sure. We’ll have to wait and see what happens.

“I’ll have a few discussions with the coach (Russell Domingo) and team selectors. If it does come my way it’d be a huge honour.”

Smith took over as captain as a 22-year-old and Domingo said: “I had an inkling that it might be around the corner with what has been happening in his life and it is a lot of pressure doing it for 12 years.

“I’m not entirely surprised but I am a bit surprised by the timing of it. His presence alone is going to be sorely missed.”

Smith will shift his focus to an English county career with Surrey, for whom he played three Championship games last season before undergoing ankle surgery.

Surrey director of cricket Alec Stewart was surprised by Smith's international exit but believes the 33-year-old will still have the drive to succeed at the Oval.

Stewart told Sky Sports 2: “I didn’t have an inkling at all. I took a phone call last night from his manager and I was thinking, ‘is he injured?’, and he just said, ‘no, he’s going to retire from international cricket but he’s very keen to continue with Surrey’.

“It was a very short time last year before he had to go home for his ankle operation but he has two years minimum with us and hopefully he can help take us forward.

"You know Graeme Smith, he's an excellent professional. He's 33, he's still got some unfinished business as far as he's concerned with Surrey."

Stewart also revealed Smith has recently qualified for an Irish passport through marriage, meaning he will not be classed as an overseas player.

Mark Boucher led the tributes from Smith's former international colleagues.

The former wicketkeeper described Smith as “a great bonus for Surrey” and added: “I think he’s getting out at the right time.

“A lot of people might say he’s still got a lot of cricket in him, and yes he has, but sometimes you know when that decision’s right to get out.”

Jacques Kallis added: "I think it came as a surprise to a lot of us. Having spoken to him a little bit I knew he was there and thereabouts but I didn't realise he was that close.

“It’s obviously a difficult call to make when this has been your livelihood for so long, it doesn’t just get made overnight.

“He’s a family man and that probably played a big role in it, and there’s lots of pressures that go with being captain.”

Another great all-rounder, Shaun Pollock, said: "He became captain at 22 and maybe he made mistakes, some people might have thought he was a bit brash, but he backed it up with performances after that.

“To have that longevity in the game is a real remarkable effort and a feather in his hat.”

Smith had described his retirement as the toughest decision of his life after ending his international career after almost 350 appearances for his country.

He said in a statement released after day Monday’s play in Cape Town: “This has been the most difficult decision I have ever had to make in my life.

“It’s a decision that I have been considering since my ankle surgery in April last year.

“I have a young family to consider, and I felt that retiring at Newlands would be the best way to end it because I have called this place home since I was 18 years old.”

Smith will leave South Africa with a major hole to fill, having been a key fixture in their line-up for well over a decade.

This, his last Test, is his 117th, of which he has been captain for 110 — a world record.

He leaves having scored 9,265 Test runs at an average of 48.26, while he has also played 197 ODIs, averaging almost 38, and 33 T20 internationals.

Smith, who has also taken 26 wickets for South Africa with his off-breaks, continued: “I have always been someone who has left everything out there on the field for my team and for my country.

“I’m extremely honoured and proud to have had the privilege to lead so many wonderful players and to have been a part of building the Proteas culture to what it is today. It is a culture that every player can be, and is, immensely proud of.”