 De Guzmán scored his first professional goal on 30 September 2005, in the Eredivisie away match against Willem II (1–3).After his debut against SC Heerenveen, De Guzmán quickly became a first team regular.On 11 December 2005, he received much praise after outplaying former Barcelona player Philip Cocu in a midfield battle at Feyenoord's Eredivisie home match win against PSV (1–0).