Tries from Cobus Reinach, Canan Moodie and Deon Fourie gave the Springboks a 21-8 half-time lead, while Jesse Kriel, Willie le Roux, Marco van Staden and Kwagga Smith added second-half scores. All seven were converted by fly-half Handre Pollard and his replacement Manie Libbok.
Ben Tameifuna, Fine Inisi and Patrick Pellegrini responded for Tonga, who made the defending champions work hard for their victory.
The Springboks have gone top of Pool B following their bonus-point win, but must now wait for the result of the match between Ireland and Scotland in Paris on 7 October to find out if they will progress to the quarter-finals.
South Africa’s head coach Jacques Nienaber knows his side will have to wait before their place in the quarter-finals is confirmed – and who their opponents will be.
“The other pool gets sorted out on Friday night and our pool gets sorted out on Saturday so it’s a waiting game,” said Nienaber.
Deon Fourie, who won the Mastercard Player of the Match having started at hooker when he normally plays in the back-row, said he had no problems with the switch.
“No, it was a good game. We expected a tough game,” said Fourie. “I’ve played hooker earlier in my career so it wasn’t too bad. It went well today and I’m glad.
“I trained there for the last two years with the Boks and our motto is: we train how we play. That paid dividends today.”
After moving into the back row when Marco van Staden came on, he added: “I must say it’s quite tough moving from hooker to flanker. The body is old but I did a good job.”
Siya Kolisi, who captained South Africa for the 50th time in tests, said: “It doesn’t matter what milestone there is, I’m always proud to be out there with this special group and hopefully we can go all the way.
“We knew they weren’t just going to lay down and give it to us. We made a couple of mistakes but we fought to the end – really proud of the guys’ effort.”
After exchanging tops with Tonga captain Tameifuna, Kolisi added: “It was a really beautiful moment, they’re a great team, really hard to play against, they put everything on the line.
“We knew it was going to be a tough game. We’re still grateful for our supporters and families who came out to support us today, hopefully we’ve done enough to qualify for the next round.”
Tonga captain Tameifuna hailed his side’s display after they scored three tries against the reigning world champions.
“It was a hard battle out there,” said Tameifuna. “This team, we don’t have a lot, but the boys turn up at this tough tournament and to put a performance like that shows where we are all heading.
“South Africa are the best in the world and it’s always tough to cross their line and we managed to do that a few times tonight.
“In these kind of games, especially with the South Africans, you have to meet fire with fire and the boys did that tonight. If we did it for longer phases we might have got a result. I’m proud of the boys.
“The crowd have been bloody awesome. I’d like to thank everyone. We just need to recover well and look forward to next week.”
Tonga’s head coach Toutai Kefu hailed his side’s performance, saying: “One of the main things we stressed before the game was putting on a performance that everyone would be proud of and that was one of them.
“That is what rugby is all about. You want to play against the best. That’s what makes the good players get out of bed so it was a fantastic experience for everyone today.”
