On Saturday night, Dan Henderson has a chance to become only the second MMA fighter in history to win a world championship after the age of 40. But at this stage of the game, championship belts aren’t what he’s striving for as much as the challenge itself. No matter how good Henderson (26-8) says he feels, his toughest long-term opponent is not Strikeforce light heavyweight champion Rafael “Feijao” Cavalcante (10-2), who he faces on a Showtime card at Nationwide Arena in Columbus, Ohio, but the one that inevitably beats everyone: Father Time. Championships are something Henderson has had plenty of for more than two decades, dating back to his teenage years in Downey, Calif., and winning the national age group championship in wrestling. So Saturday is as much about facing a dangerous younger man as it is adding to his trophy case. “I don’t think it’s a secret that both of us are going to look for a knockout,” Henderson said. “I definitely plan on trying to knock him silly, and pressure him the whole fight. “When I approach a fight, it’s about who I’m fighting, the outcome will take care of itself.