Smith and Cameron Bancroft, the fielder chosen to carry out the tampering, admitted to cheating after Bancroft was caught on television using a piece of sticky tape to rub dirt into the ball, then trying to hide the tape down his trousers when umpires suspected something was up.

Here's a look at what happened on Saturday at Newlands.

At the lunch break on the third day of the third test in Cape Town, Australia is in trouble. South Africa leads by over 100 runs with just one wicket down, looks set to forge further ahead, and the ball isn't doing much to help Australia. With the series 1-1 with one more test to play after Cape Town, it's a crucial moment in a battle between the archrivals.

Read more: Dark day for Australian cricket as Steve Smith admits plan to cheat

Skipper Smith and other senior Australia players - Smith referred to them as the "leadership group" but refused to name them - decide they will tamper with the ball when play restarts, a desperate attempt to get it to reverse swing and give their struggling bowlers an advantage. Smith said no members of the coaching staff knew about the players' intentions.

The Australians get some yellow sticky tape from a team kit bag, see if they can get some loose dirt from the pitch stuck to it when they're back out on the field, and then use it to rough up the ball.

Bancroft, an opening batsman in his eighth test, is chosen as the player to do the tampering because he is in the vicinity of the discussion between the senior players in the dressing room, according to Smith.

Confessing later, Bancroft said he was "in the wrong place at the wrong time" but denied he was pressured into doing it. As a fairly low-profile player, Bancroft appears to be a good person to do the tampering as he wouldn't normally attract too much attention when Australia is fielding.

Sure enough, Bancroft hides the sticky tape in the pocket of his trousers. When he gets the chance, he collects some "granules" beside the pitch, sticks them to the tape, and uses it on the ball.

The problem is he's caught red-handed by television cameras, and it's replayed over and over on the big screen, in close up and slow-motion. The embarrassing images are also replayed on TVs all around the world.

Australian coach Darren Lehmann appears to notice the incident on the big screen and is seen talking into a walkie talkie shortly afterward.

Peter Handscomb is also seen on the big screen with a walkie talkie and heads out into the field under the auspices of dropping off a fielding helmet. He is seen in conversation with Bancroft.

Panicking when the on-field umpires become interested, Bancroft resorts to hiding the offending piece of yellow tape down the front of his trousers.

He produces a harmless sunglasses bag from his pocket when approached by the umpires, and appears to have gotten away with it. But his desperate attempt to hide the evidence in his underwear is also caught by TV, and replayed multiple times.

Australia announces it won't be doing normal interviews immediately after the day's play with the host broadcasters, and appearing only at a news conference, at which it is unusually very late.

With overwhelming video evidence against them, Smith and Bancroft face the music at the conference, admitting everything in front of yet more television cameras. Smith said the players were desperate to try and gain some advantage because "we saw this game as such an important game."

The most immediate fallout looks set to come from Cricket Australia on Sunday. Smith, while embarrassed and regretful, said he will not resign from the captaincy.

"I still think I'm the right person for the job," he said. "Obviously today was a big mistake."

That would be a steep and sudden fall for Smith, currently the top test batsman in the world and the man who led Australia to a 4-0 Ashes rout just two months ago.

Misconduct charges brought by the International Cricket Council are also likely to be released on Sunday. Bancroft said he's been charged for ball tampering, which carries a penalty of 3-4 disciplinary points. If Bancroft receives the higher end of the punishment, he will be banned for the final test in Johannesburg.

Also intriguing is the role of Smith and the rest of the "leadership group." They could also face charges of bringing the game into disrepute. If vice-captain David Warner was part of the group, a logical presumption as the second most senior player in the team, a single demerit point would see him also banned for the final test. That could leave Australia without both of its opening batsmen.

The bigger picture is the public back home in Australia, who woke up to the embarrassing news. Australia's cricket team is its biggest sports team and as fiercely supportive as Australians are, they are also fiercely critical if the team has done wrong.

AAP