ST KILDA skipper Jarryn Geary is almost certain to be out for the season with a leg fracture after being caught in a tackle by Port Adelaide's Connor Rozee.

Geary was running through the centre of the ground when Rozee ran him down from behind, just as the Saints' veteran went to dispose of the ball. Geary then kicked himself in the back of the leg, doing the damage.

He immediately grabbed at his ankle and had to be taken from the ground with the assistance of trainers before being sent to hospital.

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The Saints confirmed in a statement the 30-year-old suffered a fractured fibula, describing it as a "clean fracture low down in his left leg".

His return to Australia won't be affected.

Football manager Simon Lethlean said everything needed to go right for Geary to appear again in 2019.

"Unfortunately, X-rays confirmed a break, which means Jarryn will be sidelined for a number of weeks," Lethlean said.

"Knowing Jarryn, he will do everything he can to be back as quickly as possible, but a return towards the very end of the season would be the best-case scenario.

"Given how hard he has worked to get back, it's obviously frustrating to encounter another setback.

"We have had a number of guys step up this season and take their opportunities and we will need that to continue in the absence again of our captain."

The way Geary kicked the back of his left leg in the process of being tackled was similar to the manner in which Bulldogs midfielder Mitch Wallis broke his leg in 2016.

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St Kilda coach Alan Richardson went into the rooms to visit Geary while play was still underway in the final quarter and was initially optimistic.

"I could just sense the doctors sense they thought it was a good sign, that he was able to put weight on it and walk out and get into the ambulance," Richardson said.

There's no doubt the hard-nosed defender will be sorely missed for however long he misses.

"To say he's popular at our footy club would be an understatement.

"What Gears will do, he won't worry about Jarryn Geary. He'll worry about his teammates and pretty quickly, because of that, his teammates will move on, because he'll demand and challenge that they do," Richardson said.

This incident continues an injury-plagued season for Geary, who was playing his first game since undergoing emergency surgery on his thigh 43 days ago.

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Richardson was disappointed with how meek his charges were in the 70-point loss to the Power at Adelaide Arena at Jiangwan Stadium on Sunday afternoon.

"This is hard to say as a coach, but they were more physical than us. They were more committed to the contest than we were. That's been a strength of ours," Richardson said.

Defenders Daniel McKenzie and Jonathon Marsh were late outs with illness, while Jack Billings and Shane Savage took to the field despite missing Saturday's training session with sicknesses of their own.

Richardson was unequivocal about the group who took to the field.

"The boys that played were right to play," Richardson said.

He suspects there wasn't much to his players going down.

"Gold Coast and Port hadn't had much issue at all (previously in China), in terms of illness. I've got a feeling we just could've been bloody unlucky. We'll look into that," Richardson said.

His only suggestion for what could be done differently was for Sandringham to have a bye when the Saints travel to China, as they will do for the next two years at least, so they could send more players over, but he acknowledged how difficult aligning fixtures would be.

Richardson backed the venture.

"I'm a fan … the guys really embraced the trip. Our footy club's embraced the whole opportunity that China gives our club," Richardson said.

St Kilda will have a bye before going up to Townsville to take on Gold Coast.

Geary is helped from the field after injuring his leg against Port Adelaide. Picture: Michael Willson, AFL Photos