AJ Allmendinger hopes a 'B' sample test will prove he has not taken any prohibited drugs, following his suspension from NASCAR after an 'A' sample tested positive last week.
Following a random test for banned substances taken at the Kentucky Sprint Cup Series race, Allmendinger was temporarily suspended last weekend and given 72 hours to ask for a further urine sample to be tested, which he requested on Monday.
The Penske driver has now issued a statement saying that he would not do anything to put his job or his colleagues' safety on the line, and that he expects to return behind the wheel as soon as the issue is resolved.
"I have informed NASCAR that I have requested that the 'B' sample be tested, following the steps according to NASCAR's 2012 rule book regarding this situation," said Allmendinger. "I fully respect NASCAR's drug usage policy and the reasons they have it.
"I am hoping this can get resolved as quickly as possible so that I can get back to driving the #22 Penske Racing Dodge. I am sorry that this has caused such a distraction for my Penske Racing team, our sponsors and fans.
"Obviously I would never do anything to jeopardise my opportunity here at Penske Racing or to my fellow drivers. I am very conscious about my training and health and would never knowingly take a prohibited drug."
Earlier on Tuesday Roger Penske told Sirius XM NASCAR Radio that his organisation continued to back Allmendinger until it understood why he tested positive in the first place, hoping that the 'B' sample draws a result that allows them to move on.
"I certainly endorse NASCAR's programme on substance abuse completely, whether it's a driver, one of our crew members, or anyone associated with the team," Penske said. "They have a process, we also have a process within our team that we do random testing.
"Obviously AJ understands the consequences. He had the first test obviously done through NASCAR's process, he failed. I understand from conversations with him that there will be a second test, I'm not sure when that'll be. But we're standing behind him until we understand the results.
"I can't really say today what that's going to be. I'm hoping that the second test will find him clean and we can move on from this situation."
Sam Hornish Jr, who replaced Allmendinger last weekend at Daytona, is set to fill in for him again next weekend at New Hampshire.