Cape Town - The Springboks' sound defensive structure has become a source of attack, defence coach John McFarland believes.The Boks scored nine tries in their 73-13 annihilation of Argentina in Soweto over the weekend and the pleasing aspect for McFarland was the fact that at least a couple of those tries were created through offensive defence."We want to use our defence as a weapon," he told the Beeld website. "You don't want to defend phase after phase because it will eventually wear you down. (But) our ability to use defence as a weapon to get points, has improved markedly over the last few years."Two perfect scenarios in Saturday's game were tries by JJ Engelbrecht and skipper Jean de Villiers. A turnover by lock Juandré Kruger from deep within the Boks' own territory was shifted through the hands before fullback Willie le Roux kicked a short ball for Engelbrecht to chase and dot down. In the second half, De Villiers also intercepted a looping Pumas pass to race in for a try."Our counter-attack has improved a lot," said McFarland. "For instance, our ability to fall back after a kick and turn that into a good attacking position, is very good this year. Player 1 to 15 knows what to do with the ball when we turn it over with good defence."The Boks have already scored 25 tries in the four Tests this year - already three more than the 22 they scored in the 12 Tests played last year.They tackle the Pumas again this weekend - in Mendoza. Kick-off is at 21:10 on Saturday.