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"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.