The Maine Cancer Foundation has switched to a new lottery registration system for its popular Tri for a Cure triathlon fundraiser.

Last year, online registration for one of the 1,000 spots available for the South Portland event was filled within five minutes, said Cullen McCough, foundation spokesman.

So this year, the foundation has set a weeklong online registration, now open through 10 a.m. Feb. 5. Participants will be selected by a third-party lottery service and announced by 5 p.m. Feb. 6.

The triathlon is scheduled for July 29.

More information on how to register is available on the Maine Cancer Foundation website at www.mainetriforacure.org