Jacques Nienaber has hinted Rassie Erasmus' social media rant allowed South Africa to focus on squaring the British and Irish Lions series out of the spotlight.

The Springboks battered the Lions 27-9 in Cape Town to level the series at one win apiece, and tee up a decisive third Test next Saturday.

The hosts won the second half 21-0 to stun Warren Gatland's Lions, with Makazole Mapimpi and Lukhanyo Am claiming well-worked tries.

Rugby director Erasmus' 62-minute online rant against officiating from the Lions' 22-17 first Test victory dominated the build-up to Saturday's second encounter.

And head coach Nienaber suggested that allowed the Springboks to focus on shoring up their approach, ahead of a convincing second-Test victory over the tourists.

"Rassie as our director of rugby had something on his mind, something that we discussed," said Nienaber. "That's off-field stuff, and we knew we had to focus on the rugby.

"So hats off to the players. We had a review, a tough week because of that, we were hard on each other. It's not just players, it's coaches as well, sometimes we get things wrong.

"But we put our hands up and say 'Listen I made a mistake there'. We just focus on rugby and the things we can control. That's basically what we did.

"The other stuff is off-field stuff and that was handled by our director of rugby, and our stuff was on-field."

Boks wing Cheslin Kolbe was fortunate to escape with a yellow card for tackling Conor Murray in the air.

But Nienaber insisted the officials made the right decision in not sending off the Toulouse speedster.

"I thought it was the right call, that they made," said Nienaber. "There's a clear process that they follow when they go through foul play.

"It would take five minutes to sit here and go through that in detail, but there's a clear process that they have to go through, and I thought it was followed to the 'T'."

Flanker Pieter-Steph Du Toit suffered a shoulder injury and is likely to miss the third Test.

"Obviously Pieter-Steph is a guy that won't come off normally in a game," said Nienaber. "But the assessment on his shoulder hasn't been done by the medical team yet; it will take 48 hours for a proper diagnosis with all the special investigations to be done. But he's not normally a guy that comes off in a game."

The Lions took a 9-6 lead into half-time but were systematically picked off by the Boks after the break, with the hosts gaining near-total set-piece dominance by the end of the contest.

Lood De Jager's introduction in the back-row allowed the Springboks to solve their line-out shortcomings, and the front-row replacements wrestled control of the scrum.

The Lions had precious few answers, leaving the entire series to hinge on the third and final Test.

Siya Kolisi had admitted feeling disrespected by referee Nic Berry in the first Test, further ratcheting up tensions after Erasmus' unprecedented online rant.

And the back-rower admitted in the wake of his side's second-Test victory that he had endured his most testing week as Springboks captain.

"That's the toughest week I've ever had to face as a leader," said Kolisi. "But I was just able to focus on the game. We knew what we needed to do, we had the same pressure as the World Cup but a bit more, because it's only every 12 years that we play the Lions.

"As a team we go back to what we know, system, structures. So now it's game on for next week."