CHARLOTTE, N.C.—A deal to loan Mark Martin to Joe Gibbs Racing as a replacement driver for injured Denny Hamlin fell apart Friday, when Michael Waltrip Racing said Martin will fulfill his commitment to its team.

When the dust settled for both teams, Brian Vickers wound up as Hamlin's replacement driver for at least four races. He was already scheduled to drive Martin's car for MWR at Martinsville next week and will keep that commitment, with Martin driving Hamlin's car.

Then Martin will go back to MWR, and Vickers will drive Hamlin's car until he's medically cleared to return from a fractured vertebra in his lower back.

The about-face came down from MWR roughly 24 hours after JGR said Martin will take over the No. 11 Toyota until Hamlin returns. He's out at least five races.

"We were a bit premature in determining Mark's status past Martinsville," J.D. Gibbs, president of Joe Gibbs Racing, said in a Friday night statement.

MWR said Martin will return to his regular car after Martinsville and "resume his previously scheduled run of events with MWR" for the rest of the season.

"I think it is great that a driver of Mark's caliber is available to support our fellow Toyota team during this difficult time for them. We wish Denny a speedy recovery" said MWR founder and co-owner Michael Waltrip. "Mark is a big part of our organization and is committed to our sponsors, especially Aaron's and Toyota. We have a lot of goals yet to reach this year and we are very focused on accomplishing them."

It's believed a deal between the teams to swap Martin for Vickers in the Sprint Cup Series races had been completed, but JGR prematurely announced it before MWR sponsor Aaron's had given its approval. No reason has been given why Aaron's didn't approve the swap.

MWR has been eyeing Vickers as a potential replacement for Martin in the No. 55 Toyota, and Vickers is scheduled to run nine races for Martin this year. Because Vickers is seen as an option for that ride, MWR was in favor of loaning Martin to the Gibbs camp to get an extended look at Vickers in its equipment.

Instead, JGR turned to a Plan B, which is Vickers, a day after Gibbs said the team wanted to use just one driver for consistency sake.

Vickers had the commitment to MWR for the first race, and Elliott Sadler, the second driver in JGR's Nationwide Series camp, already has commitments to drive the Cup races at Kansas and Talladega in a fourth car for JGR.

"Obviously, having to find someone to fill in for Denny is not an ideal situation to have to be in, and when you start a process like this you obviously begin to look at the drivers that are not only available but also able to drive for your race team and manufacturer," Gibbs said. "We're real happy to have the opportunity to get Brian in our Cup cars and with him driving Nationwide for us we think we have some continuity there that is beneficial.

"We really appreciate everyone at Michael Waltrip Racing and Toyota for working with us through this process. The good thing for us is that we have drivers the caliber of Mark and Brian to help fill in until Denny comes back."