Kenseth started 10th but dropped to 21st before the Goody's 500 was 10 laps old.
During pit stops after 42 laps, Kenseth's team was cited by NASCAR officials on pit road for losing control of one of the tires that had just been removed from his Ford.
NASCAR said it informed Kenseth's team that it was being penalized and sent to the tail end of the longest line on the restart, but Kenseth's team said it never got the message.
The miscommunication proved costly.
When Kenseth got back on the track and failed to heed the call to drop to the back, NASCAR black flagged him, forcing him to drive down pit road at the pit road speed of 30 miles per hour while the field zoomed by under a green flag, putting him a lap down when he returned.
He never recovered, finishing 23rd.
"The unfortunate thing is I wasn't clear the head official said we had to come in," Kenseth's crew chief, Drew Blickensderfer said. "I thought he was telling us, 'It was close. Make sure it doesn't happen again.' That type of thing, and it wasn't. It was, 'You messed up the rule,' so we've got to make sure we get our tires back. We can't have mistakes like that."
Kenseth has finished 43rd, 12th, 33rd and 23rd in the past four races, and he's fallen from leading the points to 12th, just seven ahead of No. 13 Jeff Burton.
------
SPEED DEMON: Scott Speed thinks Kyle Busch owes him. Speed started 36th and led 12 laps early after the leaders pitted under caution, but was spun out by Busch and sustained damage.
He headed for the garage, crashed again later and finished 39th, 76 laps down.
"I'm sure Kyle is going to offer to buy me dinner since that's the second time this year that he's wrecked me," Speed said, laughing. "So, I'm looking forward to that."
The rookie hasn't finished better than 21st in six races and fell to 38th in points, but said he's encouraged by what his team has given him to drive, and less so by his bad luck.
"We had a great car before we got wrecked and we even had a great car after we got wrecked," he said. "We had a great car but were in the wrong place at the wrong time."
------
LEADING THE CHARGE: Jeff Gordon led 147 laps at Martinsville Speedway on Sunday and moved into some rarified air in the process. He passed Fred Lorenzen for fifth on the list of laps led during his career on the 0.526-mile oval, now having paced 2,800.
The four guys ahead of him are Cale Yarborough with 3,851; Rusty Wallace with 3,632; Darrell Waltrip with 3,615; and Richard Petty with 2,964.
------
EDWARDS' CHALLENGE: Despite a third-place finish here last fall, Martinsville has always been one of Carl Edwards' most challenging tracks, and he said this weekend that winning on the paper clip-shaped oval is one of his major goals for the 2009 season.
He'll have to try again in the fall.
Edwards was running third at the midpoint of the race, but when all the leaders headed to pit road under caution on lap 254, he lost eight spots, emerging in 11th. About 25 laps later, he blew a left rear tire, went two laps down and struggled the rest of the day.
He finished 26th, two laps down.
------
LUG NUTS: Kasey Kahne and Matt Kenseth had rough starts. Kahne was sixth on the starting grid, but had faded to 19th after just 10 laps, while Kenseth dropped from 10th to 21st in the same period. ... Michael Waltrip hit the wall on lap 21, bringing out the first caution. ... Todd Bodine, Joe Nemechek and Dave Blaney started 39th or lower, and all three were in the garage before 100 laps had been run. ... Aric Almirola blew four tires during the race and then spun out on lap 446. He finished 37th.
