Franco, the older brother of PGA Tour star Carlos, was watching some old videos of his swing with his 22-year-old son earlier in the week; when the younger Franco pointed out his stance used to be more wide open.
After two days on the range, Franco regained his lost form to the tune of seven birdies and the first-round lead.
I was a little lost with my swing, so I watched some old videos from the time when I was playing well and wondered what the difference was, said Franco, who is still in search of his first European Tour victory. Now Im hitting the ball stronger. Im more comfortable.
Three Swedes are in a five-way tie for second place. Carl Pettersson, Richard S. Johnson and Olle Karlsson each shot 5-under-par 65; they are joined by Germanys Erol Simsek and Spains Jose Manuel Lara.
Defending champion Vicente Fernandez opened in 1-under-par 69. The 54-year-old Argentine is two shots back of countryman Angel Cabrera, and one shot clear of Eduardo Romero.
Former U.S. Amateur champion Hank Kuehne is in a tie for 60th place after carding a 2-over-par 72.
Full-Field Scores from Argentina Open