Officials investigating Tiger Woods' crash say there was "no evidence of impairment" as the golfing star undergoes surgery for major injuries to his legs.
Woods was rushed to hospital in Los Angeles on Tuesday with severe leg injuries, which are not believed to be life-threatening, after a horror smash saw his car overturn.
Rescue teams had to pry him from the wreckage after his car swerved into an oncoming lane then struck a curb and a tree as it careened off the road and down an embankment, authorities said.
Los Angeles County Sheriff Alex Villanueva said the dad-of-two was "lucky to be alive".
As rescuers surrounded the scene Woods was conscious and "able to communicate", officials said.
The sheriff added there was no evidence of any driver impairment when Woods was assessed by emergency workers at the scene as an investigation into the crash begins.
In a news conference, he said there was no indication that Woods was under the influence of any substances at the time of the accident.
No blood samples were drawn by investigators after Woods was rushed by ambulance to the Harbor-UCLA Medical Center.
Woods, one of the world's most celebrated sports figures, was the sole occupant of the car when it crashed about 7:12 a.m. near the suburban community of Rolling Hills Estates, the sheriff's department said.
Sheriff's deputy Carlos Gonzales, first on the scene, said Woods, still wearing his seatbelt, was "calm and lucid."
The deputy said he immediately recognised the golfing great after Woods told him his name was "Tiger."
Woods suffered serious injuries to both legs and was initially listed in serious but stable condition, Los Angeles County Fire Chief Daryl Osby told reporters.
CNN reported Woods sustained compound fractures to his legs. It was not immediately clear what effect the accident might have on his career.
Video footage from the scene showed Woods' 2021 Genesis sport utility vehicle badly crumpled and lying on its side, its windows smashed.
There were "several rollovers" before the SUV came to rest near the bottom of the hillside.
Fire department officials said emergency personnel pulled Woods from the vehicle through the front windshield after the glass and its surrounding frame were cut out and removed.
The cause of the accident was under investigation, though the sheriff said weather was not a factor and the steep and winding stretch of road "has a high frequency of accidents."
He added the distance the vehicle traveled before leaving the roadway, with no visible skid marks, pointed to the car "going at a relatively greater speed than normal."
Prayers and get well messages have poured in from friends and well wishers as the 45-year-old recovered in hospital.
Ex-US President Barack Obama tweeted: "Sending my prayers to Tiger Woods and his family tonight, here's to a speedy recovery for the GOAT of golf.
"If we've learned anything over the years, it's to never count Tiger out."
Sports stars also joined him wishing the athlete well including his ex-girlfriend Olympic skier Lindsey Vonn.
She tweeted: "Praying for TW right now."
Retired baseball star Alex Rodriguez said on Twitter : "Praying for my brother Tiger Woods as we all anxiously await more news."
"Thinking of him and his entire family."
