Two-time Indianapolis 500 champion Al Unser Jr. was arrested on a charge of operating a vehicle while intoxicated, according to an online jail record.
Bond was set at $300, according to the record at the Hendricks County (Indiana) jail. He was arrested by the Avon Police Department and booked at 3:21 a.m. ET on Monday, according to the record.
An Avon officer pulled over Unser's vehicle shortly after 1 a.m., clocking it going 59 mph in a 45 mph zone and drifting from its lane, according to court documents. The officer later noticed Unser's eyes were red and glossy and his speech slurred.
Unser said he hadn't been drinking. He staggered to the rear of the vehicle after exiting the car, lost his balance, fell to the ground and rolled down an embankment, the documents said.
Blood was drawn from Unser after he refused to take a field sobriety test. Results were pending.
Unser, 57, retired from racing in 2007. He is currently an executive consultant for the Harding Steinbrenner Racing IndyCar team.
"The entire Harding Steinbrenner Racing organization is saddened to learn of Al Unser Jr.'s arrest on an OWI charge. Alcoholism is a disease and a continuing battle for those struggling with it. At this time, we do support Al in any way that he needs," the team said in a statement, adding that any further questions should be directed to Unser's attorney, James H. Voyles.
Voyles declined to comment Monday when contacted by The Associated Press.
Unser has struggled with alcohol abuse for several years.
He pleaded guilty in 2012 to driving while intoxicated and racing on a New Mexico freeway stemming from a 2011 arrest, and pleaded no contest to a driving under the influence charge in Nevada in 2007.
In 2002, he underwent treatment for alcohol abuse after his then-girlfriend said he hit her in the face while he was drunk in Indianapolis. Prosecutors didn't file charges.
He is the son of four-time Indy 500 champion Al Unser, and a nephew of three-time Indy winner Bobby Unser. Al Unser Jr. won the Indy 500 in 1992 and 1994, and he won two CART points titles and two IROC championships.
The Associated Press contributed to this report.