South Africa, who topped Pool C, will face Pool B winners Ireland in the semi-final on Sunday, while the other top-four playoff will be between England, who finished second in Pool B, and Pool A winners France.

Playing with intensity and tiring out the Argentineans, who were kept scoreless after the break, the Junior Boks did what was needed and if it wasn’t for a couple of close scoring opportunities in the second half, the margin could have been wider.

But the South Africans won’t complain about the score, as all they needed was victory, although they made life difficult for themselves at times.

If playing against the stiff breeze in the first half wasn't tough enough, the South Africans also played into their opponents’ hands with bad discipline and a basically non-existant set piece.

Conceding penalties at regular intervals - three of which were turned into points by Argentinean flyhalf Valentino Dicapua while there was also a disallowed maul try - meant the South Americans were on the front foot for most of the first half.

The hosts were made to defend for large periods of the first half, which they did with gusto, although there were a few slipped tackles.

The Junior Boks had a handful attacking opportunities which they failed to convert, but in the 27th minute they finally got some reward for showing patience in Los Pumitas' 22 when Juann Else (hooker) went over for the first try of the match. Flyhalf Jean Smith converted to make it 9-7.

But when JF van Heerden (lock) was sent to the sin bin four minutes later for a maul infringement, Argentina struck when burly prop Renzo Zanella crashed over for a try, with Dicapua's conversion restoring their nine-point lead.

Smith made it 16-10 early in the second half after which the game turned into a real arm-wrestle as the Argentineans tried to play, and the Junior Boks tackled and tackled, interspersed by some good attacking plays by the fleet-footed backs, while the pack also considerably upped their game.

The home team had a few close calls, once when fullback Hakeen Kunene was over but the TMO spotted a foot in touch by Jurenzo Julius (wing) during a strong run, and again later when they were held up over the tryline.

That didn't deter them however, and with 11 minutes remaining, the irrepressible Corne Beets (No 8) crashed over for a try, converted by Smith, that gave the Junior Boks the lead for the first time in the game.

Six minutes later Beets, who was named the Mastercard Player of the Match, sealed the deal with his second try, also converted by Smith, which gave the Junior Boks an eight-point lead.

Scorers:

Junior Springboks 24 (7) – Tries: Juann Else, Corné Beets (2). Conversions: Jean Smith (3). Penalty goal: Smith.

Argentina U20 16 (16) – Try: Renzo Zanella. Conversion: Valentino Dicapua. Penalty goals: Dicapua (3).