Clarkson has been hospitalised with Gullain-Barr?aacé syndrome (GBS), which is an inflammation of the nerves from the spinal cord and is is expected to remain in hospital for the next week, with a timeline for his full recovery is yet to be determined.

The 46-year-old was taken to hospital on last night with back pain which had become more acute over the previous two days.

``We're fortunate that Alastair's condition has been detected early, and were confident he is in the best possible hands under the care of very experienced specialists,'' Hawthorn chief executive Stuart Fox said today.

``Our primary concern is for Alastair's health and a timeline for his return to coaching is not a consideration at this stage.

 ``The club will provide support for Alastair and his family for as long as it takes him to recover.''

Fox said Bolton had the full support of the club as he steps into the senior coach role for  ``as long as may be required''.

``Having worked together for six years, Alastair and Brendon share very similar coaching, teaching and management philosophies,'' Fox said.

``With the support of the other assistant coaches, development coaches, leadership group and players, we are confident Brendon's transition as temporary senior coach will be seamless.''

Bolton, who played for North Launceston and North Hobart, coached Hawthorn in its 65-point NAB Cup win over North Melbourne in February, and usually looks after the Hawks' forward-line. 

He also coached North Hobart, Clarence and the Tassie Devils and Box Hill in the VFL.

Hawthorn takes on Greater Western Sydney at the MCG on Sunday, before playing its second match at Launceston's Aurora Stadium for the season against West Coast the following Saturday.