Dennis Shelley took his share of punches many years ago as a college boxer but the hardest blow he ever felt came Christmas Eve in the parking lot of Graton Resort & Casino in Rohnert Park.

The 68-year-old American Canyon man walked out to his car around sunrise after a night spent “losing money” at the baccarat tables.

Shelley, who is diabetic, was planning to take his daily insulin injection when two men came from behind, grabbed his arms and demanded cash. The retired Army sergeant major wrestled with the taller of the two before the other one bashed his head with something solid.

“I’ve never been hit so hard in my life. Ever,” Shelley testified Tuesday in a preliminary hearing for the two men, who are now in custody. “It felt like a wooden object, like a bat or two-by-four. And I was out cold.”

The next thing Shelley remembered was crawling on the ground, looking for his wallet, glasses and phone. Paramedics came and drove him to Santa Rosa Memorial Hospital, where doctors told him he had suffered a concussion.

When he got around to checking his belongings, Shelley realized his wallet containing up to $5,000 and two diamond rings were gone.

Detectives from the Sonoma County Sheriff’s Office got to work right away.

Surveillance videos of the casino floor and parking lot showed two Santa Rosa men, Ricardo Davalos, 21, and Devante Raushad Love, 20, watched Shelley at the high-limit gaming tables and followed him outside. They were arrested after casino security guards recognized Love as a cook in a casino restaurant.

Despite an extensive search, Shelley’s possessions were never recovered. Detective Adrian Mancilla said the case marked the first robbery at the casino since it opened Nov. 5.

A judge this week said there was enough evidence to try them on charges of robbery, assault with force likely to create great bodily injury and cruelty to a dependent adult.

Meanwhile, Shelley, a self-described frequent Indian casino gambler, is still suffering the effects of the attack. He said he has memory problems, headaches and dizziness.

“My whole life has changed,” Shelley said. “It’s difficult to walk. It’s like I’m walking on a ship on the ocean.”

Read coverage of the attack here  and on the pair’s arrest here