SYDNEY teenager Tom McCartin has received medical clearance to return to training after suffering dizziness from a collision with a teammate three weeks ago. 

Swans coach John Longmire said the 19-year-old would resume contact work next Monday and push for practice match selection in late March. 

"It's fantastic news," Longmire told AFL.com.au

"He's all good, he's all fine, there's not a problem at all and he doesn't require any further attention. 

"It's not a concussion issue, he had some dizziness after the knock, and he's now fine to get back into it." 

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McCartin and his family were extremely worried about his condition when an MRI of his neck revealed concerns relating to an artery. 

But subsequent tests and analysis allayed fears his season, and even career, could be finished, when it was diagnosed that the problem was one McCartin was born with. 

"We didn't tell any of our players because we wanted to get all the facts, and now we have got those facts," Longmire said.

"When something has the potential to be serious, you don't jump to conclusions and that's why we waited. 

"While the potential of it being serious was there, we waited until Monday. It has been there since birth. 

"The family was very concerned, as you would be. The results coming out of the scan had nothing to do with the knock, but at one point no one knew what it was." 

McCartin, the Swans' second pick at No.33 overall in the 2017 NAB AFL Draft, was the youngest AFL-listed player in the 2018 season. 

He played 15 matches in his debut year, including a round 20 match at the SCG where he kicked a late, match-winning goal against grand finalist-to-be Collingwood. 

Tom's brother, the St Kilda-listed Paddy McCartin, travelled to Sydney early in the week for support.

"He was the youngest kid in the AFL last year, played 15 games at centre half-forward when we lost Sam Reid; he's a great young bloke with a great family," Longmire said. 

"They've had an anxious week and fortunately it has turned out well."