RICHMOND, Va. -- In a performance not befitting a champion, Tony Stewart eliminated himself from title contention with a miserable showing at Richmond International Raceway.

The two-time and defending series champion fell apart this weekend, starting with a wreck that destroyed his primary Chevrolet minutes into the first practice and capping it with a lackluster 18th-place finish in Saturday night's race.

Stewart, who said earlier this season he deserved to be fired if he ever missed NASCAR's chase for the championship, plummeted from eighth to 11th in the series standings and won't be eligible to race for the Nextel Cup title when the postseason begins next week.

"It takes 26 weeks to get to this point,'' Stewart sighed after climbing out of his backup No. 20 Chevrolet.

"This is proof of how tough this series is and how tough it is just to make this Chase. It's a big letdown obviously, but at the same time there's 10 guys there that earned their way in, too, so we've just got to wish those guys good luck now.''

Stewart can now finish no better than 11th in the final standings, guaranteeing him the worst finish of his career. Stewart's previous low was sixth, in 2000 and again in 2004, the first year of the Chase.

Kasey Kahne, who came into the race 11th in the standings, benefited from Stewart's downfall to claim the final Chase position. Kahne finished third in Saturday night's race -- behind winner Kevin Harvick and Kyle Busch-- to get NASCAR's leading winner into the Chase.

"I didn't ask one time where the points were until we crossed the start/finish line,'' Kahne said. "I was hoping we were in, and we were.''

Kahne has five wins this season, and his possible exclusion from the Chase had ignited a debate over whether NASCAR needed to award more points for victories. Before the race began, NASCAR officials said adding bonus points for wins is under serious consideration for 2007.

But it does no good this year for Stewart, who could have benefited from extra points for his two wins this season. He wound up 16 points out of 10th place.

Even worse, his rookie teammate will go on to race for the title without him.

Denny Hamlin is the surprise of the Chase field, overcoming a faulty engine Saturday night to finish 15th and earn his spot in the playoffs. He's fifth in the standings.

The Chase begins next Sunday in New Hampshire, where 2003 series champion Matt Kenseth will take a five-point lead into the 10-race postseason over Jimmie Johnson.

Harvick is in third and is followed by Busch, Hamlin and Dale Earnhardt Jr. Mark Martin, in what is expected to be his final full-time Cup season, is sixth and is followed by Jeff Burton, Jeff Gordon and Kahne.

Harvick, with three wins now this season, is suddenly the dark horse of this title pursuit. Needing only to finish 40th or better to make the Chase, he could have been conservative here at Richmond. But that's not his style, and he ran for the win instead of the points.

``I was scared to ask, to be honest with you,'' Harvick said. ``It was something where as soon as I asked, I figured something would go wrong.''

Harvick passed Busch as he headed to the white flag and pulled away for the win.