(AP) -- Denny Hamlin suffered a compression fracture in his lower spine during a last-lap crash while racing for the win against former teammate Joey Logano, and Joe Gibbs Racing gave no indication Monday how long its driver could be sidelined.
"I just want to go home," Hamlin tweeted from a hospital in Southern California. He later posted a photo of himself giving a thumbs-up and appeared to be wearing a back brace.
The team said he had what is called an L1 compression fracture; essentially, the first vertebra in the lumbar section of his spine collapsed.
Hamlin was released from the hospital Monday night, and JGR said he'd return to North Carolina to be evaluated by Dr. Jerry Petty of Carolina Neurosurgery and Spine Associates. A reporter from USA Today spoke to Hamlin outside the hospital and reported Hamlin, wearing a back brace, walked out on his own.
NASCAR does not race this weekend, but returns to action April 7 at Martinsville Speedway, where Hamlin, who is 10th in the Sprint Cup standings, is a four-time winner.
Hamlin was airlifted from the Fontana track after a collision with Logano sent him nearly head-on into the inside wall in a place where Auto Club Speedway does not have energy-absorbing SAFER barriers. There are barriers on the inside of some of the walls, but portions of the track between Turns 1 and 2 and Turns 3 and 4 are not protected.
Track spokesman David Talley said Monday the SAFER barriers are installed upon NASCAR's recommendation, and track officials will wait to see what, if anything, NASCAR recommends after Hamlin's accident.
"NASCAR is reviewing the incident and any improvements that can be made, will be made," Talley said. "If NASCAR feels that additional SAFER Barriers are needed, then we will absolutely make those enhancements. SAFER barrier recommendations are based on past history and this is a situation we, nor NASCAR has ever seen at this track before."
IndyCar last year returned to Auto Club Speedway for the first time since 2005 and the season finale is scheduled to be held at the track in October.
But the issue of the SAFER barriers and Hamlin's impact seemed to be overshadowed by the most recent flare-up in this new feud.
Logano managed to finish third despite wrecking into the outside wall after hitting Hamlin, who spun Logano last week at Bristol to spark a bitter post-race confrontation.
Because of the recent bickering between the former teammates, Logano was somewhat defiant after Sunday's accident.
"He probably shouldn't have done what he did last week, so that's what he gets," Logano said.
On Monday, Logano's car owner said the driver was unaware of Hamlin's condition when he made the comment during a television interview.
"That's a tough thing, Joey had no idea what the situation was with Denny when he was doing the interview," Roger Penske said. "It's one of those things that came out and taken out of context isn't what he meant. He can't take it back, but people are certainly blowing that up to mean something different than what he knew at the time."
Tony Stewart also got into a post-race shoving match with Logano, who aggressively blocked Stewart on a late restart. Stewart claimed Logano threw a water bottle at him when he approached, but crews separated the two before it turned into a full fight.
Stewart later railed against the 22-year-old Logano in several interviews and accused him of being "nothing but a little rich kid that's never had to work in his life."
Logano was 18 when he broke into NASCAR with Joe Gibbs Racing in 2008 with the nickname "Sliced Bread." He'd risen rapidly through the racing ranks with the financial backing from his father, Tom, who used funds from the family's Connecticut waste management company to help his two children pursue their dreams.
Logano had the means to pursue a racing career, and was in Georgia racing quarter midgets at the age of 6 while his older sister chased a life of competitive ice skating.
But Tom Logano's near-constant presence at the NASCAR races hurt Logano's reputation, and him angrily demanding his son go after Kevin Harvick after a 2010 incident at Pocono only made things worse.
On Monday, Patricia Driscoll, girlfriend of Kurt Busch, referred to Logano as (hash)TrustFundRacer in a series of tweets that accused him of reckless racing with "no less than 5 drivers."
"We were lucky that none of the others were hurt by his actions," Driscoll tweeted.
An agitated Penske thought the criticism of Logano's upbringing was out of line.
"He's a solid young man and his family has supported him in racing as many families of professional athletes do in every sport," Penske said. "Anyone who looks at that as a criticism, to focus on that is just petty."
He also said he supported his driver, who signed last year to join the Penske Racing organization as teammate to defending Sprint Cup Series champion Brad Keselowski.
"Listen, Joey is a great driver and what happened at the end there wasn't anything more than hard racing," Penske said. "I stand behind him and I think he's going to go down as one of the greatest drivers to ever race."
It never developed at JGR, where Logano replaced Stewart in 2009 and was teammates with Busch and Hamlin. Signs of a rift between Hamlin and Logano didn't show publicly until after this year's season-opening Daytona 500, when the two exchanged barbs on Twitter.
Then came an on-track incident at Bristol last week, more exchanges on Twitter, and finally their last-lap battle for the win at Fontana. Although the crash seemed to be a result of hard racing, Logano's lack of empathy immediately after the race gave the impression his contact with Hamlin was intentional.
Hamlin got himself out of the car, but then slumped to the ground beside it before an ambulance arrived. He was eventually airlifted out due to traffic around the track.
The injury is a bit more common in open-wheel racing, which has had three incidents of drivers breaking their backs since 2009.
Will Power broke several vertebrae in his lower back in a 2009 crash during practice at Sonoma and missed that event and the final three races of the season. He couldn't train for two months and wore a back brace for almost four months.
He also suffered a compression fracture of his fourth thoracic vertebra in the 2011 season finale at Las Vegas but missed no racing as he healed during the offseason.
Justin Wilson fractured his fifth thoracic vertebra in 2011 and missed the last six races of the season. Wilson said he was in a back brace for 10 weeks.
Three-time Indianapolis 500 winner Dario Franchitti fractured the L1 vertebra in his back in a 2003 motorcycle accident. He needed surgery and was out of a race car for almost nine months.
In NASCAR, Sterling Marlin missed the last seven races of the 2002 season with a fractured vertebra in his neck.