Former South African captain Faf du Plessis has revealed the Proteas’ suspicions of Australia’s treatment of the ball during the infamous ‘Sandpapergate’ series went back well before the scandal was unearthed in Cape Town.

In his upcoming autobiography Faf: Through Fire, du Plessis writes that the team began to obsessively watch Australia in the field during the second Test of that series, after a fierce spell of reverse-swing from Mitchell Starc in the first Test inflamed their belief that something was amiss.

“During the first Test in Durban, the Australian pace attack had got the ball to reverse insanely,” du Plessis writes.

“Mitchell Starc claimed nine wickets and, although I regard him as one of the best proponents of reverse-swing bowling I have ever seen or faced, those deliveries in Durban were borderline unplayable.

“He would come in around the wicket with a badly deteriorated ball and get it to hoop past us.

“Our balls had also reversed but not nearly as much as theirs.

“We suspected that someone had been nurturing the ball too much to get it to reverse so wildly, and we watched the second Test at St George’s through binoculars, so that we could follow the ball more closely while Australia was fielding.

“When we noticed that the ball was going to David Warner quite often – our changing room must have looked like a birdwatching hide as we peered intently through our binoculars.

“There was a visible difference between how Mitchell Starc got the ball to reverse in the first Test in Durban and the final Test in Johannesburg. We now know that there was an obvious reason for that.”

Steve Smith and David Warner were banned for 12 months over the incident in March 2018, while Cameron Bancroft, who was caught applying sandpaper to the ball, received a nine-month suspension.

Warner is still banned from any leadership role within the Australian cricket team.

However, du Plessis also admitted to his and the Proteas’ own indiscretions with ball-tampering, including a much-publicised incident in Australia in late 2016 when he was caught using a mint to apply saliva to the ball.

Cameron Bancroft of Australia talks to the umpire. (AP Photo/Halden Krog)

The 38-year old argued that Smith ‘didn’t do much wrong’, expressing ‘tremendous sympathy’ for Bancroft’s ordeal in particular.

Notably, du Plessis excluded Warner from this defence.

“I’m not mentioning this from atop a high horse. In the past, we have also been found guilty of employing unorthodox methods to get the ball to reverse swing,” du Plessis writes.

“In our team, we just thought, ‘Nah! Ball tampering and reverse swing have always been there.’ In fact, it was probably more prevalent when camera technology wasn’t as good as it is today.

“Personally, I don’t think Steve Smith did much wrong. It’s no secret that all cricket teams want the ball to reverse. Not everyone knows how to accomplish this, especially not inexperienced players. But everyone knows it’s wrong to change the condition of the ball. We, too, have pushed those boundaries.

“Steve Smith and I have never been friends but we always played a hard game against each other, and Steve had been willing to defend me publicly in 2016 when ‘Mintgate’ broke.

“I texted him that evening [in Cape Town]: ‘Message of support. Gone through this myself. It is a terrible experience when they attack your character. Hang in there. It will blow over.’

CLICK HERE for a seven-day free trial to watch the T20 World Cup on KAYO

“He responded, ‘Thanks mate!’ To which I replied, ‘There will be a s–tstorm for a while. But stay strong.’

“I have tremendous sympathy for what he [Bancroft] went through. This is what happens in a team when the culture of belonging is restricted to performance and when players are made to believe that they need to prove themselves at any cost before they feel accepted.”

Du Plessis’ autobiography will be released on October 28.