HOMESTEAD, Fla. (AP) - In the six years Dario Franchitti had been driving for Chip Ganassi, he had only phoned his boss once from his home in Scotland.
When Ganassi got a call this week, and heard the tone in Franchitti's voice, he knew something was off.
''The first thing out of my mouth was, `What's wrong?''' Ganassi said Friday.
Franchitti was calling to deliver difficult news: Doctors had told him it was too dangerous to continue racing because of injuries he sustained in an Oct. 6 crash at Houston when his car sailed into a fence. The three-time Indianapolis 500 winner fractured his spine, broke his ankle and suffered a concussion that day.
The threat of another concussion put Franchitti at too great a risk to continue racing, Ganassi said. Franchitti reluctantly announced his retirement Thursday.
''He was certainly heartbroken,'' Ganassi said. ''He's a bit of a realist about it, too. I went through all the obvious questions. He said, `Look, I don't want to go forward. I'd never want to go forward and risk hurting somebody else or risk further injury, much less hurt somebody else.' He wouldn't dare risk giving a black eye to the sport or something by trying some sort of end around. That was out of the question. He respects professionals.''
Franchitti had two surgeries on his broken ankle, one in Houston and one in Indianapolis, before traveling in the last two weeks to Miami to see IndyCar consultant Dr. Steve Olvey. The 40-year-old Franchitti then returned home to Scotland to continue his recovery.
He was in Scotland when he was advised to stop. Olvey, the associate professor of Clinical Neurology/Neurosurgery at the University of Miami-Miller School of Medicine, told RACER.com that Franchitti has suffered three concussions since 2002 and the one at Houston ''was a big one, a significant concussion.
''He's got a higher risk for future concussions with less energy involved in a crash,'' Olvey told RACER. ''And, as we've seen in pro football, repeated concussions can lead to early dementia, so he's got to think of his future. It's just too great a risk to take.''
Ganassi said Franchitti will heal.
''Medically he has been told he'll make a 100 percent recovery, we've been told that from day one,'' Ganassi said. ''These are all injuries that are recoverable. I don't want anybody thinking he's maimed for life.''
But he won't be in the No. 10 Target car again, and Ganassi is now searching for a driver. He said he will field four cars next year, but isn't sure if moving defending Indianapolis 500 winner Tony Kanaan into Franchitti's car is an option; Kanaan was signed last month with different sponsors.
Ganassi, who had passed on signing James Hinchcliffe last month, now has to see who might be available.
''The obvious question is, do you go with a proven talent in that car or do you go with a young up-and-comer?'' Ganassi said. ''We've always taken the best driver that's available at the time. That car is part of a team that for years has run at the front of the pack, and everything that goes along with running at the front in terms of scoring points for championships and helping teammates win championships. That's not always the best position for a young, up-and-coming driver to come into. I'm not saying it can't be done, but we have to look at all available options right now.''
Ganassi said replacement drivers has not been a priority this week as the organization has been attending to Franchitti, who said in his announcement he wants to remain involved with IndyCar in some capacity.
Franchitti's retirement was still reverberating through the sport. Jimmie Johnson, who goes for his sixth NASCAR championship Sunday, said he feels horrible for his good friend.
''In one light, it shows just how bad his crash was. I'm just happy he is in good health,'' Johnson said. ''My heart goes out to him from the perspective of having racing taken from him before it was time. That's got to be so tough to deal with. Everyone wants to walk away on their terms.''
Formula One driver Jenson Button said Franchitti made ''the right decision'' and praised his friend for his career accomplishments - even if he's not properly recognized in Europe for his achievements.
''He's a long way away from Europe and a lot of American motorsport doesn't really get the credit in Europe,'' Button said at the U.S. Grand Prix. ''It is what it is. It's just a long way away. I don't think it matters how many compliments he gets. He knows what he's achieved and the people he cares about know as well. A very impressive career and he's a great guy as well.''
Franchitti's mentor, Jackie Stewart, said the four-time IndyCar champion is exiting on top and will be an asset outside of the car.
''There's not much more he could achieve in American motor racing,'' Stewart said at the U.S. Grand Prix. ''I think he's one of the real players in the business. He's got a strong future in front of him because of the success he's achieved in racing. Sad for motor racing because he's a great asset to us: A great looking guy, very eloquent and he's very fast.''
Franchitti also could be the unofficial face of the importance of baseline concussion testing in racing.
NASCAR is mandating the testing beginning next season, in part because of the two concussions Dale Earnhardt Jr. suffered last year. NASCAR will use the ImPACT test to measure verbal and visual memory, processing speed and reaction time, and determine if a driver is medically able to race following a concussion.
NASCAR President Mike Helton did not say Friday that Franchitti's injury validated NASCAR's decision to implement the testing. But he acknowledged the industry takes note when a champion driver has to get out of the car. Three-time NASCAR champion Tony Stewart has been out since August with a broken leg, and Denny Hamlin missed several races earlier this year with a fractured vertebra.
''I think it has a huge effect on all of the motorsports industry when a caliber of driver like Dario says he's not going to get back in the car,'' Helton said.
Defending NASCAR champion Brad Keselowski has been outspoken in his opposition of the testing, which has long been required in IndyCar.
''Doctors don't understand our sport. They never have. Doctors aren't risk takers. We are,'' Keselowski has said. ''That's what makes our sport what it is. When you get doctors involved, you water down our sport.''
While not asked specifically about Keselowski, Ganassi referenced his stance while supporting the testing.
''Let's just say I'm probably 180 degrees different than the current NASCAR champion feels about having doctors around, their input,'' he said. ''That statement comes from experiences that I've had personally. To break a bone is one thing, or to have a surgical procedure is another.
''But when it comes to your head, I think it's important that everybody understands that's probably the least known area of expertise by any doctor, and certainly there's a lot of expertise out there. They're just in the last four or five years understanding what injuries and implications of those injuries are.''