Although Basque-born (in Bilbao), Ríos emerged through the youth system of Real Betis, making his professional debut in the Segunda División in the 1992–93 season.

In summer 1997, following rumours of a transfer to Manchester United earlier in February, Ríos was signed by Athletic Bilbao for 2 billion pesetas, a then-record for a national player.

[2] In his first season, he netted twice in 32 games (including once in a 5–1 home win over CP Mérida, on 21 December 1997)[3] as the Basque side finished runners-up in La Liga.

However, in January 2003 he rejected a contract offer from the Gary Megson-led team, stating "I don't want to fool anyone" about his chances of regaining full fitness.

[6][7] Ríos was capped 11 times by Spain,[8] with his debut coming on 9 October 1996 in a 0–0 away draw against the Czech Republic in the 1998 FIFA World Cup qualifiers.