WAIT a minute, pilgrim – is that rugged-looking John Wayne lookalike really The Duke’s grandson?

You bet, pardner. He’s Brendan Wayne, who will guest star in an episode of “CSI” set to air in January.

In the episode, called “Bull,” Grissom (William Petersen) and the “CSI” gang investigate a murder at the rodeo.

Brendan, 35, was born Daniel LaCava, the son of The Duke’s late daughter, Toni Wayne.