South Africa bounced back from their surprise defeat to Japan by thumping Samoa 46-6 to clinch a bonus-point victory at the Rugby World Cup.

The rugby world had been stunned as Japan secured a thrilling 34-32 success over the two-time champions last weekend to blow Pool B wide open.

But there was to be no repeat at a raucous Villa Park on Saturday as a hat-trick from JP Pietersen and one score each from Schalk Burger, Schalk Brits and Bryan Habana secured a maximum five-point return.

South Africa struggled in the earlier periods of the match as Samoa demonstrated their customary physicality in the contact area, but ultimately the underdogs, who began their tournament with a 25-16 win over United States, could not emulate the feats of Japan. 

For Springboks coach Heyneke Meyer, who made eight changes to his XV from the Japan game, victory was a welcome relief after a week of scrutiny and his side will now look ahead next Saturday's clash against Scotland with renewed confidence. 

Roared on by thousands of their supporters, the Springboks began well and aggression at the breakdown brought a first-minute penalty which Handre Polland duly converted, but they were soon behind as Samoa responded strongly.

Michael Stanley twice punished South African transgressions with successful kicks - the second of which sailed over from halfway.

But the Samoa fly-half undid that good work on the quarter-hour mark as his attempted miss-pass was intercepted by Pietersen, who sprinted clear to touch down.

Pollard missed the extras, but he was more accurate shortly afterwards to further extend the lead to 11-6.

Samoa were physical throughout, with TJ Ioane responsible for a pair of massive hits on Adriaan Strauss and Burger, but another Pollard penalty kept the Springboks ticking over.

The two-time champions thought they had a second try when skipper Jean de Villiers went over, but Willie le Roux was deemed to have gone into touch just before offloading to his captain.

Instead South Africa were forced to settle for another Pollard three-pointer to take a 17-6 lead into the break, but they pulled further clear six minutes after the restart when Pietersen had the simple task of dotting down from an overlap on the right.

The Springboks became more dominant as the half wore on, and had their third try just prior to the hour as Burger held off the attentions of replacement Ole Avei to get the ball down.

Samoa thought they had their first score through Tusi Pisi, only for it be ruled out for the final pass being forward, and their pan was exacerbated as Brits sealed the bonus point after a rampant driving maul.

As Samoa visibly tired, Pietersen completed his hat-trick before Habana raced clear down the left to complete the rout and round off an excellent day for Meyer's men.