Junior Boks assistant coach Nazeem Adams says a quick turnaround in performance is needed before they take on Argentina on Saturday.

The SA U20s overcame a first-half scare against Pool C opponents Japan with an excellent second-half display to clinch a 59-19 win in their opening game on Tuesday. But while they outscored Japan eight tries to three, Adams admits there were several deficiencies in their game.

'There are a few areas of our game that require a vast improvement before the Argentina clash, such as our breakdowns and defence, and we have to make sure that we play for the full 80 minutes,' said Adams. 'We were a little frantic in the beginning [against Japan], and we made too many unforced errors, but luckily we managed to turn things around in the second half.'

Argentina kicked off their tournament with a 24-15 victory against France and Adams expects a tough challenge from the young Pumas.

'They will target our breakdowns, so we have to be physical at the contact points. The players have Wednesday off to recover and then we will have two training sessions on Thursday and the captain's run on Friday. We have to make the most of the time we have on the training field to work on the areas of our game that were lacking against Japan.'

Saturday's match kicks off at 19:00 with the team being announced on Friday.

Junior Boks coach off to Japan

Photo: Matthew Lewis/Getty Images