He grew up in the Town of Ba and he played for Lautoka in the National Provincial Rugby Tournament in Fiji. He was picked to represent Fiji in the Rugby Sevens. He scored 85 tries for the Fiji sevens. In 1999 Delasau was named Player of the Year at the Fiji Rugby Awards after scoring 82 tries in the season. He earned his first Test cap against the US Eagles in June 2000 after impressing in the sevens form of the game the previous year. He also holds the record for scoring the most tries in a sevens game with 6 tries and also the record of most tries in a tournament with 16 tries, followed closely by fellow Fijian winger, Rupeni Caucau on 14 tries.
In April 2010 he joined Toulouse as a medical joker as they suffered numerous injuries. Montauban suffered a points deduction for financial irregularities and will be relegated at the end of the 2009/2010 season. He scored his first try against Castres on just his second game for his new team.
In February 2012, he retired from International rugby.