A man charged over an alleged hit-run crash that left Adelaide cyclist Matthew Rex critically injured is Rex's training partner Chris Jongewaard, News Ltd newspapers reported.

Jongewaard, 27, of the Adelaide suburb of Para Hills, was arrested Monday night over the crash two nights earlier that left Rex, 22, in an induced coma, they said.

A past competitor in the Tour Down Under, Rex was riding with another person along Main South Road at Normanville, south of Adelaide, about 9pm (ACDT) Saturday when he was hit.

The other rider was not injured.

Rex was taken to Adelaide's Flinders Medical Centre.

Jongewaard has been charged with dangerous driving, causing injury by dangerous driving, driving without due care, failing to stop at an accident scene and failing to render assistance, the report said.

Police were awaiting the results of a blood-alcohol test.

Jongewaard, who was to leave for the United States next month for his professional racing debut, was bailed to appear in the Adelaide Magistrates' Court on February 20.

He was to race in America for several months before joining the Australian mountain bike squad for the second half of the 2007 European season.

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