Canada's Peter Reid, the prohibitive favorite for the inaugural race, pulled out of the event May 10 due to a foot injury.
The injury, a stress fracture, occurred during a half-Ironman race in Mexico.
Reid, who won the 1998 Ironman World Championship in Kona, Hawaii, is the only North American ever to break eight hours in an Ironman race.
Reid's departure meant that there was no clear-cut favorite for the May 20 Ironman California. But that all changed the following day when Australian Chris Legh announced his intention to race.
Legh, who bounced back from a dismal performance at Ironman Australia with an impressive win May 7 at the Wildflower half-Ironman, is ready to notch another win, according to Ironman California Race Director Buzz Mills.
"Chris is definitely an athlete on the upswing," Mills said. "He should definitely be a force here at our inaugural event."
Legh is considered one of the sport's up-and-comers. He has bounced back from a near-fatal bout of dehydration suffered at the 1997 Hawaii Ironman. Following the race, Legh underwent emergency surgery and had a portion of his small intestine removed.
According to Ironman California Media Director Shane Facteau, the field of 20 elite men may get even stronger in the days to come with the possible addition of the reigning Hawaii Ironman World Champion.
"Luc Van Lierde is in town," Facteau said. "There are no definites, but he may be a late entry."
Van Lierde, also a winner at Hawaii in 1996, is coming off a win May 7 at the St. Croix International Triathlon.
In the women's race, veteran triathlete Jan Wanklyn is another a late entry that threatens to contend for a podium spot.
Wanklyn, who has five Ironman victories under her belt, joins Heather Fuhr and Melissa Spooner as a favorite in the elite women's race.
The race will be held in and around Camp Pendleton Marine Base and the city of Oceanside. More than 1,800 athletes from 45 countries are expected to start the race.