In 1988, Külvet surpassed his best decathlon with a score of 8506 points in Staiki, Belarus. This achievement placed him second in the world that season, just behind Christian Plaziat of France.
Alhama de Murcia decathlon of 1997 is remembered for its exceptional performances. It contributed to the rich history of the decathlon as one of the most challenging and prestigious events in track and field athletics.