Huntersville, NC -- (Sports Network) - Two-time Cup Series champion Tony Stewart has been granted a release from the final year of his contract with Joe Gibbs Racing, a move that will take effect at the conclusion of the 2008 season.

Stewart will finish the 2008 Sprint Cup season driving the No.20 Toyota for JGR, and will compete in two more Nationwide Series races for the racing organization, including Friday night's race at the Chicagoland Speedway.

Stewart's contract with JGR was originally set to run through the 2009 season.

"We've had a lot of success with Tony in our 12 years here at Joe Gibbs Racing," said J.D. Gibbs, president of JGR, in a team statement. "While this moment is bittersweet, we're parting on good terms and we know that each of us has benefited greatly from the other."

Stewart had a prosperous 12-year tenure with JGR, including Cup championships in 2002 and 2005. He also recorded 32 career victories and finished top-10 in points in eight of the last nine seasons.

Stewart joined the team in a developmental role in 1997, while pursuing his quest for the Indy Racing League title. The following year, JGR expanded his Nationwide schedule to 22 Nationwide races in preparation for his 1999 Cup rookie campaign.

With a then-record of three wins in his first season, Stewart captured rookie of the year honors in 1999.

Stewart's parting from JGR and crew chief Greg Zipadelli at the conclusion of the 2008 season will end the longest active driver/crew chief relationship in the Cup garage.

"We've accomplished so much in our 10 years together on the track, and off the track, he's been like a big brother to me," Stewart said of Zipadelli. "It's a friendship I cherish and expect to continue, even while he stays at Joe Gibbs Racing and I move on."

Stewart is currently 12th in the championship standings, and holds just a two- point advantage over 13th-place Kevin Harvick with eight races remaining before this year's "chase" begins. The 12th spot is the cutoff point for "chase" eligibility. Stewart is the defending winner at Chicagoland.

Stewart is expected to make an announcement on Thursday regarding his future NASCAR plans.