In March 2002 he was handed a start against Arsenal in the UEFA Champions League due to Juventus rotating their squad having already qualified for the next round.
When Juventus were relegated to Serie B for the Calciopoli scandal in 2006, Guzmán re-joined the Old Lady in their quest to return to the Italian top flight and signed a contract extension to June 2010.
At Juventus, Guzmán had the oppritunity to work alongside fellow strikers and world champions Alessandro Del Piero and David Trezeguet, along with Marcelo Zalayeta, Valeri Bojinov, Raffaele Palladino, and Sebastian Giovinco.
After not finding much playing time at Juventus, he was loaned out to Spezia for the remainder of the 2006–07 Serie B season.
After a decent time with Spezia, he was farmed to Piacenza Calcio for the 2007–08 Serie B season, in co-ownership deal.