Prop Thomas Gallo scored two tries as Argentina produced a sparkling attacking display to smash depleted Australia in their Rugby Championship match in San Juan.Argentina crossed twice in the first six minutes and feasted off the Wallabies' lack of experience to run in seven tries in their biggest victory over Australia and their largest in the southern hemisphere competition.Wingers Juan Imhoff and Emiliano Boffelli, centre Jeronimo de la Fuente, flanker Juan Martin Gonzalez and replacement out-half Tomas Albornoz also crossed for the Pumas, who took advantage of Australian errors in ruthless fashion.The Wallabies scored tries through captain James Slipper and centre Len Ikitau, but bar a brief spell in the opening half never really threatened the hosts as the absence of several leading players due to injury and personal reasons took its toll.Only five of Australia's starting 15 had more than 30 caps and they never got to grips with Argentina's intensity, having beaten the Pumas 41-26 last weekend in Mendoza.The home side kept applying pressure with ball in hand and attacking kicks, and while the bounce of the ball favoured them, Australia were also their own worst enemies in not dealing with the threat.Argentina scored in the opening minute as Imhoff chased his own kick and when the ball was fumbled by Australia full-back Tom Wright, was able to race clear.One try quickly became two as the home side powered over the line from close range, Gallo providing the finish touch.The fast start continued as Australia finally got possession and after a barnstorming run from No 8 Rob Valetini, Slipper crossed to score.De la Fuente and Gonzalez punished Australian errors for two more tries in a helter-skelter first half that ended