WESTERN Bulldogs midfielder Tom Liberatore will be sidelined "indefinitely" after entering concussion protocols for the second time in three weeks.

Liberatore suffered a concussion during the club's loss to Hawthorn on Sunday, having collapsed in concerning scenes during the loss to Essendon in round five.

Having entered concussion protocols after the Bombers' game and missed the win over St Kilda in round six, Liberatore was then absent for the loss to Fremantle due to a stomach bug before returning to the senior side against the Hawks on Sunday.

The club says the concussion occurred late in Sunday's game, when Liberatore copped a stray boot from Hawk Conor Nash. The midfielder also suffered a head knock in the opening minutes of the game in a collision with Karl Amon, but was cleared by medicos to return to the field.

But he'll now spend an extended period on the sidelines.

"The midfielder suffered a knock to the head late in Sunday's loss to Hawthorn, with the club's medical team confirming that a concussive episode had occurred," the Bulldogs said in a statement.

"Having suffered two concussions within a short space of time, Tom will be unavailable for an indefinite period as the club works through a thorough process before a return-to-play plan is determined.

"Tom's health and wellbeing always remains the absolute priority during this period."

The 31-year-old would have missed this week's game against Richmond in any case after copping a one-match ban from the Match Review Officer late on Monday.

Liberatore passed a SCAT6 concussion assessment in the rooms after the final siren of the Essendon game last month and didn't display any symptoms in the week after the match. However, he was placed into concussion protocols as a precaution after the concerning vision of him collapsing late in the game emerged.

He was then put through a range of medical tests, assessing him for cardiovascular and respiratory issues, and was medically cleared.

"It's something I can't really comment on because I saw him stumble in the middle of the ground and that's concerning," coach Luke Beveridge said after Sunday's game.

"For it to happen again this afternoon when it was only a couple of weeks ago the same thing happened, it's a bigger concern than a one-week issue.

"We'll take a conservative approach, we'll look after him."

Liberatore entered the AFL's concussion protocols twice last year following incidents against Fremantle in round seven and Hawthorn in round 22.