Updated Nov 28, 2011 4:46 PM ET



Tony Stewart made a decision to fire crew chief Darian Grubb, and winning the NASCAR championship didn't change his mind.

Offseason changes
Big Movers
Not all Cup stars are staying put after 2011. WHO’S ON THE MOVE?.

Grubb was officially replaced Monday, eight days after guiding Stewart to the Sprint Cup title. Steve Addington, who quit as Kurt Busch's crew chief last week, takes over immediately - and begins work as Stewart and Grubb head to Las Vegas to begin the championship celebration.

''I know Steve well and I know how he goes about setting up a race car,'' said Stewart, who worked with Addington from 2005 through 2008 during his time at Joe Gibbs Racing.

''My comfort level with him is already strong. He balances the technical part of our sport with the real-world experiences we get at the track, and that will allow for a smooth transition as we prepare to defend our title in 2012.''

Grubb was told midway through the Chase for the Sprint Cup championship that he was going to be let go at the end of the season. Stewart had gone winless through the first 26 races of the season, but opened the Chase with back-to-back wins to become a sudden title contender.

But the Stewart-Haas Racing team stumbled, and Stewart made the decision to replace Grubb.

Grubb then led Stewart to three more wins, including a powerful drive in the Nov. 20 season finale to give Stewart the title over Carl Edwards. It was Stewart's third championship.

After the race, Grubb acknowledged he'd been told he was not coming back next season, and Stewart declined to discuss his crew chief's status.

''Darian was a very important part of the success we've had at Stewart-Haas Racing,'' Stewart said Monday. ''I'm very proud of everything he helped accomplish, especially this year when we all rallied to win the championship. He's a great person and I know he'll continue to be successful in this sport.''

Grubb won't stay off the market long: Rick Hendrick said Monday he's offered Grubb an engineering position with Hendrick Motorsports, where Grubb was before he became Stewart's crew chief in 2009.

Hendrick said he was surprised Grubb was let go.

Star power
Three-time champ Stewart's impact goes beyond driving.

''I think the dye was cast before the Chase, and then they had the Chase, they had the success and they won it, but it was something they just didn't want to go back on,'' Hendrick said. ''Darian is a very smart guy, and he's entertaining a lot of offers out there.

''I hope Darian ends up with us. I think he would help our organization a lot, but I'm not sure - if he wants to be a crew chief, we don't have that spot.''

Addington, meanwhile, becomes just the third crew chief of Stewart's 13-year career. He won his previous two titles with Greg Zipadelli at JGR.

Addington has won 16 races as a crew chief, all with brothers Kyle and Kurt Busch. He led Kyle Busch to 12 wins at JGR, but was let go with three races remaining in the 2009 season. He then moved to Penske Racing to team with Kyle's older brother, Kurt, and led him to four wins and consecutive berths in the Chase.

Addington also spent 15 years as a crew chief in the Nationwide Series, winning 10 races with Jason Keller.

''Tony and I are a lot alike and we're able to push each other,'' Addington said. ''I saw how he worked when we were at Gibbs together and I'm not surprised at all at the success he's created at Stewart-Haas Racing.

''He expects a lot and he knows a lot. His talent behind the wheel is obvious, but his ability to motivate and get everyone to believe that whatever goal they set is attainable is something every crew chief wants, and I plan to make the most of it.''