Updated

South Africa are wary of Samoa before they clash in a four-nation tournament final on Saturday despite a string of large victories over the Pacific islanders.

Springbok winning margins of 52 points twice, 50, 42, 28 and 27 were achieved with the only 'respectable' defeat suffered by Samoa being 13-5 at the pool stage of the 2011 Rugby World Cup.

Only five of that South African side will run out at the 52,000-seat Loftus Versfeld stadium while there are seven Samoan survivors from the team beaten at Albany in New Zealand

South Africa coach Heyneke Meyer has been impressed by the form of the islanders during the mini-league phase of a tournament featuring Test double-headers on three consecutive weekends.

Star left-wing Alesana Tuilagi bagged a brace of tries as Samoa outmuscled Scotland 27-17 in Durban and another five were scored last weekend in a 39-10 trouncing of Italy in Nelspruit.

It was a pleasant change from the Samoans' first weekend in the republic this June when a side lacking several stars suffered a humiliating 74-14 loss to demoted Super 15 outfit Golden Lions.

"Samoa have a strong squad and are benefiting from their best players competing in the Super Rugby championship and at top club level in Europe," warned former Northern Bulls coach Meyer.

The Springboks survived some second-half hiccups to down Italy 44-10, but did not seal a flattering 30-17 victory over Scotland until substitute centre Jan Serfontein snatched a last-minute try.

Serfontein, skipper of the 2012 IRB World Junior Championship-winning team, is among several newcomers this season as Meyer seeks to broaden his player base ahead of stiffer Rugby Championship (formerly Tri-Nations) challenges.

Crowd favourite Willie le Roux, a free spirit who plays on the right wing for Central Cheetahs, gets a third outing in a row at full-back and former wing JJ Engelbrecht has looked comfortable at outside centre.

Arno Botha was impressive at flank until an early injury against Scotland ended his season, and gave Siya Kolisi a chance to star as he continued a rags-to-riches rise from township poverty to wearing the green and gold.

Meyer has shuffled his pack for Samoa after a disappointing showing at the breakdown against a Scottish side lacking several key forwards, including injured skipper Kelly Brown.

Powerful ball carrier Willem Alberts is back in place of Botha to get the Springboks over the gain line more often and the return of 'scavenger' Francois Louw, who was married last week, should ensure plentiful ruck and maul ball.

"We underperformed and underachieved against Scotland," admitted Louw from English Premiership club Bath, "but it was a lesson well learnt. You need those games to put things into perspective".

There is also a change at lock with 120-kilogram Flip van der Merwe replacing lighter, line-out specialist Juandre Kruger, and teaming up with Eben Etzebeth as Meyer seeks greater engine-room options.

After a decade of legends Victor Matfield and Bakkies Botha lording line-out battles against all-comers, it has come as a shock to Springboks supporters when rivals steal some throws.

Samoa, skippered by outside centre Paul Williams because wing David Lemi is injured, favour an unstructured game which lets Tuilagi and company loose to demonstrate their power and pace.

However, neither Williams nor recalled full-back James So'oialo possesses the match-winning goal-kicking skills of South Africa playmaker Morne Steyn, and it would be a shock if the Springboks did not claim first place.

The Loftus double-header kicks off with a third-place play-off between Six Nations championship rivals Italy and Scotland, who won 34-10 when they last met five months ago in Edinburgh.