Minnesota Vikings running back Ian Johnson had a scary collision during a recent "Organized Team Activity" session, Chip Scoggins of the Star Tribune reports.

"I’m just running my route and my eyes are always fixed on the quarterback. So as I’m getting width I don’t know what’s coming. I trust the quarterback that he’s not going to throw me into a headache.

"I got hit by something and go up over my feet, end over end. I did a flip. My first instinct was, 'Oh, I’m going to hurt whoever this was because someone just cheap-shotted me' I look up and I see it’s Coach Childress. He’s on the ground and I’m like, 'Oh no, that’s my ticket out of here.' You don’t do that to the head man.

"I sat there for about two seconds and he popped up and said, 'Oh, I’m sorry. That’s my fault.' I was like, 'Whew, maybe I’m not out of here.'"

An undrafted free agent out of Boise State, Johnson ran for 117 yards with a team-high 2 touchdowns during the 2009 pre-season before spending his entire rookie season on the team's practice squad. Johnson will challenge Albert Young for the third running back spot on the Vikings' depth chart, behind Pro Bowler Adrian Peterson and second-round pick Toby Gerhart.