Grubb was suspended in March 2004 for failing a drug test, but agreed as part of his reinstatement this June to random testing. But when NASCAR officials approached him after Friday night's Busch race, he twice refused to submit a sample, spokesman Jim Hunter said.

``He did not give any reason Friday night, he just refused twice to submit to a test and part of his reinstatement was that he would agree,'' Hunter said. ``Our medical liaisons have experience and know what they are doing, and they explained the consequences to him several times.''

Although Grubb wrecked on the first lap of the Busch race and finished last, Hunter said the test was random and NASCAR was not accusing him of being under the influence of any illegal substances.

Grubb, from Mechanicsville, Va., was first suspended following a race at North Carolina Speedway in February 2004.

He was required to attend a rehabilitation program and was subjected to random drug tests during the two seasons he was out. Although he agreed to random tests, Hunter was unsure if Grubb had been asked to submit a sample before Friday night.

Grubb was thankful for his second chance in an interview with The Associated Press following his reinstatement. He had spent his time away from the sport working with his father's crane business in Virginia.

``It was probably something that needed to happen. I needed to get my life together and get my priorities in line. That's really what I've done. I've changed a lot, and it'd be nice to come back racing and concentrate more on racing,'' Grubb said. ``The biggest thing was I got myself straight, and things followed after, so I'm going to keep on the right road and see what's laid in front of me.''

Grubb has made five starts in the Busch Series and four in the Truck Series this season. His highest finish in Busch was a 10th-place finish in St. Louis in July.