Confronting footage of concussed Vickery emerges

Video has emerged showing a clearly concussed Ty Vickery trying to take a mark despite the ball being nowhere near him.

The confronting footage shows Vickery leap for the non-existent ball before stumbling to the ground.

Richmond have reviewed the tape but are still searching for answers as to how he suffered the concussion during the Tigers' NAB Challenge clash with Fremantle.

Opponent Alex Silvagni alerted an umpire to Vickery's state and he soon left the field.

Questions were raised as to whether he may have suffered heat stroke in the mid-afternoon match, but the club has ruled that out.

Physical Performance Manager Peter Burge said the tall forward would undergo concussion tests this week, but won't play on the weekend.

"We take a strong approach to that (concussion), and we have to go through a few hoops before we could consider him to play."

It's not the first time we've seen a head knock cause athletes to do strange things: