Sigalas helped Olympiacos Piraeus to win a EuroLeague title in 1997, as well as to make two more EuroLeague Finals appearances, in 1994 and 1995. With the senior Greek national team, he competed in six consecutive EuroBasket tournaments, (1993, 1995, 1997, 1999, 2001, and 2003), and he made it to the semifinals on the first three occasions. Sigalas was also instrumental on the Greek teams that made the semifinals of both the 1994 FIBA World Championship and the 1998 FIBA World Championship, as well as on Greece's team that finished in fifth place at the 1996 Summer Olympic Games.