Traffic is being diverted after a young motorcyclist was seriously injured in a crash at a busy Adelaide intersection on Sunday.

The motorcycle collided with a car on Goodwood Rd and Greenhill Rd about 8am, South Australian Police said.

A man in his 20s was seriously injured in the crash.

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He was taken to the Royal Adelaide Hospital.

The two major roads have been temporarily closed as emergency services continue their work at the scene.

Goodwood Rd is closed to all traffic between South Tce and Rose Tce.

Greenhill Rd is closed to all traffic between Anzac Hwy and Greenhill Rd. Westbound traffic will be diverted south onto Goodwood Rd.

“Motorists are advised to avoid the area,” SA Police said.