TOM BELLCHAMBERS will miss the start of the season after requiring ankle surgery on Tuesday, sidelining him for at least three months. 

The Essendon ruckman was initially set to miss only four weeks after straining ligaments last week, but visited a specialist who decided the 24-year-old needed to repair the injury.

The improving big man, who kicked 28 goals last year in 18 games, will miss the NAB Challenge series and is in serious doubt for the start of the home and away season.

It is a big blow for the Bombers, who have only two ruckmen – Bellchambers and Paddy Ryder – on their senior list.

"To lose a player of Tom’s ability for that amount of time is not ideal, but we have to look at the positives and Tommy is a resilient character," Essendon coach Mark Thompson said.

"Tom will have the full support of the fitness and medical team to help him get back out playing as soon as possible.

"We have a number of quality players that can play in the ruck including Paddy Ryder and Joe Daniher, and we picked up Fraser Thurlow in the rookie draft over the summer."

Thompson last week told AFL.com.au he wasn't concerned about a lack of ruck options.

"If our second one goes down then we'll use our third one, so we've got enough. If you lose three you'd be horribly stiff and then we'll probably use the next tallest," Thompson said.

"We haven't got a problem, and I haven't got a problem, with the ruckmen situation."

Bellchambers has played 61 games since making his debut in 2008, and was seen as likely to hold down more time in Essendon's forward line this year as a marking target.

Twitter: @AFL_CalTwomey