Cheslin Kolbe claimed a try double as South Africa eased to a 49-3 bonus-point thumping of 14-man Italy to stand on the brink of the Rugby World Cup quarter-finals.

Italy could have reached the last eight for the first time with a win on Friday, but they were well beaten at Shizuoka Stadium Ecopa as the ruthless Springboks moved top of Pool B.

There were uncontested scrums for much a one-sided encounter after the Azzurri lost both tighthead props to injury and Conor O'Shea's side lost a third prop when Andrea Lovotti was sent off early in the second half.

South Africa were already in control when Lovotti was dismissed, following first-half tries from the excellent Kolbe and Bongi Mbonambi, and they ran away with it in the second half.

Kolbe, Lukhanyo Am, Makazole Mapimpi, RG Snyman and Malcolm Marx crossed after the break, while Handre Pollard scored 14 points to become South Africa's all-time leading World Cup points-scorer.

Rassie Erasmus' men will surely be in the quarter-finals, with a final pool clash against Canada to come, whereas Italy must pull off an unlikely victory over New Zealand to progress for the first time.

Simone Ferrari limped off with a hamstring strain only two minutes in, and Kolbe added insult to injury by taking a superb cut-off pass from Willie le Roux and stepping in off the right flank before finishing clinically.

Pollard added the extras and was also on target with a penalty after Tommaso Allan got the Azzurri on the board from the tee.

Referee Wayne Barnes instructed there would be uncontested scrums for the rest of the match due to Marco Riccioni becoming the second Italy tight-head prop to be withdrawn, but South Africa were relentless as they took a firm grip on the contest.

In-form hooker Mbonambi dived over at the back of an unstoppable driving maul and Italy were all-but beaten when Lovotti and Nicola Quaglio inexplicably lifted Duane Vermeulen before ploughing him head-first into the turf, resulting in the former being given his marching orders.

The Rugby Championship holders showed no mercy, with lively wing Kolbe taking a cross-field kick from Pollard to grab his second try and Am intercepting Jake Polledri's pass to coast over.

Mapimpi ploughed through a gap to go under the posts and Kolbe forced an error from Matteo Minozzi to gift Snyman a score, before Marx finished from the back of a driving maul as Italy wilted.

Springboks make a statement

South Africa were clinical in attack and rock solid in defence, showing why they have been tipped as strong contenders to lift the Webb Ellis Cup.

They made a blistering start, driven on by their powerful forwards with strong runners and kept a high tempo throughout, with their classy backs also tormenting Italy as they sent out a statement.

Italy left to rue misfortune and indiscipline

Springboks head coach Erasmus declared scrum-time would be one of the biggest challenges South Africa would face, but that battle never materialised due to Ferrari departing and his replacement Riccioni following soon after.

Riccioni appeared to take a heavy bang to the ribs and after also undergoing a head injury assessment, he was unable to play any further part. Such was South Africa's power up front, it is unlikely that would have changed the outcome and Lovotti's rush of blood summed up Italy's evening.

What's next?

South Africa should make light work of defeating Canada in Kobe City on Tuesday, with Italy facing the huge task of locking horns with the All Blacks next Saturday.