Yeley, 32, will drive the No.41 car for Mayfield Motorsports beginning with this weekend's Sprint Showdown, the 40-lap preliminary event for the NASCAR Sprint All-Star race at Lowe's Motor Speedway.

"I've been in the car; I've been fitted [in a seat]," Yeley told NASCAR Scene. "These guys here, it's probably more of a throwback to what I've been used to most of my racing career - an underdog team with a handful of guys that have the heart to win championships and win races."

Yeley has 95 career Cup Series starts, with his best finish of second coming in May 2007 at Lowe's. He spent half of the 2008 season with Hall of Fame Racing before the team released him in August. Yeley drove for Joe Gibbs Racing in his first two full Cup seasons from 2006-07.

Mayfield, 39, was randomly tested earlier this month at Richmond. He became the first driver to be suspended since NASCAR's revised drug policy went into effect this season. Mayfield said in a statement that a combination of prescribed and over-the-counter medications resulted in a positive drug test.

This year, Mayfield formed his own Cup team and qualified for five races, including the Daytona 500. His team is currently 44th in owner points.

NASCAR revealed its new substance abuse policy last September, with all drivers and crew members tested at the beginning of the year and subject to random tests throughout the season.

The policy for testing someone who is of "reasonable suspicion" remained in effect.

Penalties for violating the policy remained the same, with immediate suspension from competition. While it is possible that a competitor could receive a lifetime ban for just one violation, a third violation will automatically result in a lifetime ban.