A wipeout, and it’s lights out

NBC is going "Ninja."

On Monday night, the network airs the third-season finale of "American Ninja Warrior," the extreme-obstacle-course athletic event carried by its tiny cable sibling G4 that could prove a test of the show's viability on a major network.

Already it's G4's highest-rated series. Now NBC viewers will see 10 finalists who weathered tryouts and a training "boot camp" trek to Japan to compete in the four-stage course for the chance to win a $500,000 endorsement contract.

Unlike ABC's "Wipeout," played for broad laughs, "Ninja Warrior" is serious business, a variation on a niche sport known as parkour. It's an Americanized version of "Sasuke," a …