St Kilda defender Dylan Roberton is likely to miss one to two weeks as he undergoes a series of tests following his frightening collapse during the Saints' weekend loss to Geelong.

Saints' football manager Simon Lethlean told the media on Monday afternoon that Roberton was waiting for an ultrasound test at the Epworth Hospital.

"When he gets those [test] results back if they come back normal he'll be released from hospital today and come back home and join his family," Mr Lethlean said.

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Roberton had lined up for a centre bounce in the second term on Sunday at Kardinia Park when he suddenly fell to the ground.

Concerned teammates and Saints medical staff quickly attended to the 26-year-old and he was able to walk off the ground.

Earlier in the day, Mr Lethlean told Melbourne radio RSN the initial diagnosis had been an irregular heartbeat.

Robertson had no previous history of heart issues.

At the media conference, Mr Lethlean acknowledged there was no certainty the collapse was heart-related.

"When that [collapse] happens, and you saw how it happened, you have to take things very seriously," he said.

"It could be a viral issue, it could be anything but obviously the heart is what is going to be looked at."

The Saints official said in addition to the ultrasound, there were a series of tests to be undertaken whenever there were issues related to the heart.

"In the short term, he'll have a number of different tests, and each of those results will dictate where he goes thereafter," Mr Lethlean said. "There'll be no exercise in the meantime, so at least you imagine a one or two-week margin (off) and see how we are from there."

Mr Lethlean said Roberton's teammates were distressed about the uncertainty over his wellbeing.

"They were a bit shaken up, as you would be if you saw your mate go down like that, we kept them posted at each break [of his condition].

"The review of the game last night was more about Dylan's health, advising where he was and who was there. That's how we deal with a pretty tight playing group."

Gregson injures foot again for Cats

Meanwhile, Geelong forward Cory Gregson suffered another foot injury during the win over the Saints.

The Cats are worried, given Gregson missed all last season because of an injury on the same left foot.

"He's a bit sore but he doesn't know and [the doctors] don't know so we'll just have to wait," Cats coach Chris Scott said.

"Sorry to be so vague on it but I think everyone sits back on their seat and is a bit concerned, and fair enough, so we should be."

Hawks set to lose Rioli, Puopolo

Hawthorn are set to lose Cyril Rioli (knee) and Paul Puopolo (hamstring) for several weeks after they were hurt in Sunday's big win over Melbourne.

Carlton is awaiting word on the severity of captain Marc Murphy's left-foot injury.

Murphy pulled out of the side only moments before the first bounce of Saturday night's big loss to North Melbourne in Hobart.

He felt discomfort in his foot during the warm-up.

ABC / AAP