South Africa are on the brink of the Rugby World Cup quarter-finals after a bonus-point victory over Tonga.

The vital fourth try came through Jesse Kriel before Willie le Roux, Marco van Staden and Kwagga Smith went over.

The game between Scotland and Ireland next Saturday will decide the final order of Pool B.

Gregor Townsend's side now need to beat Ireland and deny Andy Farrell's team a bonus point in Paris next Saturday to qualify. If they manage it, Springboks will top the pool.

However, a combination of a bonus-point win for Scotland and a losing bonus point for Ireland will leave all three sides on 15 points, meaning it will come down to points difference for the top spot and head-to-head for the second spot.

Tonga came into the World Cup with hopes as high as ever thanks to the recruitment of former All Blacks George Moala, Vaea Fifita, Malakai Fekitoa, Charles Piutau and Augustine Pulu following a change in World Rugby's birthright amendment rule.

But they have suffered three heavy defeats to Ireland, Scotland and now South Africa. Next Sunday's match against Romania, who have also lost all their games, will offer an opportunity to end their disappointing tournament on a high.

Pollard perfect from the boot

Jacques Nienaber made 12 changes to the Springboks' starting line-up after their 13-8 defeat by Ireland, which included the long awaited return of 2019 World Cup winning fly-half Handre Pollard.

Regular fly-half Manie Libbok has struggled with his goal-kicking so far this World Cup after missing two crucial attempts against Ireland.

Pollard, who has only played 30 minutes since May due to a calf injury, kicked all four of his conversions - the first from the touchline - to show exactly why Nienaber decided to draft in the fly-half for the injured Malcolm Marx.

But it was his half-back partner Reinach who had the first meaningful contribution of the match when his quick tap caught the entire Tonga side napping as he raced over for an early try. A moment of good fortune then gifted Moodie the second score of the evening when the ball cannoned off the shoulder of prop Vincent Koch.

The world champions had only conceded 16 points in their first three games and, despite large amounts of early possession, the Pacific island nation found out just why that green and gold brick wall is so hard to break down.

Captain Ben Tameifuna eventually powered his way over to grab a much deserved try for Tonga, after hooker Fourie scored from a maul for the world champions.

Pollard was replaced on 50 minutes by Libbok, who responded to criticism with his own touchline conversions from Le Roux's and Van Staden's tries, as the holders ran out comfortable winners.

Line-ups

South Africa: Willie Le Roux; Grant Williams, Canan Moodie, Andre Esterhuizen, Makazole Mapimpi; Handré Pollard, Cobus Reinach; Ox Nche, Deon Fourie, Vincent Koch; Eben Etzebeth, Marvin Orie; Siya Kolisi (captain), Duane Vermeulen, Jasper Wiese.

Replacements: Marco van Staden, Steven Kitshoff, Trevor Nyakane, Franco Mostert, Kwagga Smith, Jaden Hendrikse, Manie Libbok, Jesse Kriel.

Tonga: Salesi Piutau; Fine Inisi, Malakai Fekitoa, Pita Ahki, Anzelo Tuitavuki; William Havili, Augustine Pulu; Siegfried Fisi'ihoi, Paula Ngauamo, Ben Tameifuna (captain); Halaleva Fifita, Sam Lousi; Tanginoa Halaifonua, Sione Talitui, Semisi Paea.

Replacements: Sam Moli, Tau Koloamatangi, Sosefo Apikotoa, Adam Coleman, Sione Vailanu, Sonatane Takulua, Patrick Pellegrini, Afusipa Taumoepeau.

Referee: Luke Pearce (England)