 He made his La Liga debut on 11 April 1999 when he played injury time against Real Zaragoza at the age of 18, thus becoming the first player to have represented the club in all categories; his breakthrough came during 2001–02, when he only missed five league matches and scored his first goal (in the first league round and against Zaragoza) but also received his first red card, during a 0–2 away loss against city rivals FC Barcelona.Lopo would remain a starter at Espanyol under several coaches (Juande Ramos, Javier Clemente, Luis Fernández and Miguel Ángel Lotina) until his departure, gaining in the process a reputation as a superb but excessively rough defender.In 2002–03 he was booked 13 times in 23 games, including two in a 2–5 loss at Racing de Santander.