Key Australian track cyclist Alex Porter has a potentially serious shoulder injury, two months out from the world championships.
Porter crashed halfway through the 50km madison on Saturday night in the national titles at Melbourne Arena.
He left the velodrome infield in a wheelchair, with his left arm in a sling.
Porter's helmet had been split in two by the impact, but his shoulder injury is understood to be the major concern.
He started the Australian team pursuit squad in their world-record win at the April Commonwealth Games.
Porter combined with Leigh Howard, Kellan O'Brien and Sam Welsford to ride three minutes 49.804 seconds - the first quartet to break 3:50.
His injury comes ahead of the February world titles in Poland, where Australia will resume their fierce rivalry with Great Britain, the reigning world and Olympic champions.
"It's a bit of a blow to his worlds preparation, but we're still not exactly sure about the nature of his injury," Australian men's team pursuit coach Tim Decker said.
"We will make sure he gets the best treatment, so he recovers as quickly as possible."
Howard and O'Brien won the madison on 56 points, just one clear of Welsford and Cameron Scott.
While it was a painful night for Porter, the madison win was the second title on the night for Howard and O'Brien.
They were key members of the Victorian squad who easily beat top qualifiers South Australia to defend their Australian team pursuit title.
Howard and O'Brien combined with young gun Luke Plapp and starter Godfrey Slattery to ride 3:56.588 and beat SA, featuring Porter, by more than four seconds.
Decker noted Victoria's time was quicker than the 3:59 from the British, who won the latest World Cup round in London.
On Thursday, Plapp won the emerging athlete category at the Australian Sports Commission Awards.
Welsford was in the WA team who won the bronze medal.
Queensland caught SA in the women's team pursuit final, while the NSW Institute of Sport won the bronze medal.
Sprint ace Kaarle McCulloch, who bypassed the London World Cup round to be in a heavy training block, led NSW to their first women's team sprint championship in seven years.
McCulloch combined with Sophie Knox to qualify fastest on Thursday and teamed with Selina Ho on Saturday to beat Victoria in the final.
Two teenagers won the prestigious Austral wheelrace handicap finals, also held on Saturday night.
Australian junior keirin champion Sam Gallagher, 17, took out the men's race off a 90m mark.
Stephanie Corset, the daughter of 2010 Australian road race champion Ruth Corset, won the women's Austral.
The 16-year-old rode off a 165m handicap.
Kristina Clonan and Maeve Plouffe won the women's national madison title.
The Australian championships are split this summer, with several events to be held in February in Brisbane.
