South Africa looked a very different team, in personnel as well as execution, in the slippery Pukekohe conditions.
Samoa are not a wet, cold weather side, but their line speed on defence and bruising running close to the rucks caused the Junior Boks some major headaches. They even managed to upset some of their vaunted lineouts and drives with their aggression as the "malosi" cries rang out around ECOLight Stadium.
South Africa seemed to invariably find the hard point of a Samoan shoulder, though Nathaniel Apa sailed too high in taking Sergeal Peterson around the head in the second half, for which he was sinbinned.
Captain Henry Stowers and fellow loose forwards So'otala Fa'aso'o and Richard Mariota led the charge. Samoa had already showed promising signs in pushing New Zealand hard, and beating Scotland 27-18 on Friday on the same ground.
There was not a penalty goal attempt until the 27th minute.
That was missed by William Talataina-Mu, but then the energised Samoans struck, charging down Jesse Kriel for 2013 NZ Schools rep Apa to score.
South African No7 Jacques Vermeulen was held up over the line, and No8 Aidon Davis dived across the whitewash after a powerful South African scrum for their opening try.
Yet Samoa went to the break with a deserved one-point advantage courtesy of a Talataina-Mu penalty.
South Africa missed several attacking opportunities including Davis coughing up the ball from an intended pushover scrum.
It just wasn't happening until Andre Esterhuizen slid over after a dominant scrum and Petersen put the result beyond doubt.
South Africa 21 (Aidon Davis, Andre Esterhuizen, Sergeal Petersen tries; Handre Pollard 3 cons).
Samoa 8 (Nathaniel Apa tries; William Talataina-Mu pen).