During his tenure, he played understudy to the likes of Carlos Navarro Montoya; on 16 May 1993, in a reserve game against Club Atlético Independiente, a clash with an opponent resulted in head trauma, a depressed cheekbone, orbital fracture and torn ligaments, which sidelined him for nine months.
[2] On 8 July 1999, Herrera moved to the Spanish La Liga after signing a three-year contract with Deportivo Alavés for 200 million pesetas.
[3][4] He was an undisputed starter in his first year, being awarded the Ricardo Zamora Trophy with only 37 goals conceded (all 38 matches played),[5][6] which was good enough to qualify to the UEFA Cup after the sixth-place finish.
[7] Herrera continued to be first choice for the Basques in the following season, but was also briefly suspended by the Royal Spanish Football Federation for allegedly holding a false Italian passport.
[8] He later succeeded in proving his origins,[9] and helped his team reach the final of the UEFA Cup on 16 May 2001, a 5–4 extra time loss against Liverpool after an own golden goal.