Larrieu was surprisingly made first choice for the 2001–02 season but this decision proved to be a masterstroke. Plymouth became champions of Division Three (now League 2) with Larrieu conceding only 28 goals, keeping 27 clean-sheets (a club record) and pulling off many a fine save. He was also named in the PFA Division Three team of the year. He was again first choice for the 2002–03 season as he became a fan favourite at Home Park. After that he was linked with a shock move to then Premiership champions Arsenal. But his 2003–04 season was cut short after 6 games after sustaining damaged knee ligaments. Argyle won promotion from Division 2 (now League 1) that season, and in 2004–05 he shared goalkeeping duties with Luke McCormick in the Championship.