ALLEN PARK — When Calvin Johnson doesn’t practice, inquiring minds want to know why.

The Lions wide receiver was on the field Thursday, but had no helmet and didn’t participate other than stretching.

Afterward he said he was healthy.

“I’m fine, I’m fine, I’m fine,’’ Johnson said.

He said he would find out later on Thursday just how much he’ll play in the preseason opener on Friday night against Cincinnati at Ford Field.

“I’m definitely looking forward to a little competition, getting out there on the field,’’ Johnson said. “Been away for it for a minute, to finally get some live action it’s going to be good for us.’’

Other than Thursday, Johnson and Matthew Stafford have provided most of the offensive highlights during camp.

Johnson said as long as he gets in the right spot, Stafford will get him the ball.

Game is set for 7:30 p.m. on Friday. It will be tape-delayed on ABC-Channel 7 with a 9 p.m. pre-game and 9:30 p.m. kickoff. It will re-air on the NFL Network at 10 a.m. on Saturday. (Follow me on Twitter @PaulaPasche throughout the game.)