A motorcyclist is being treated for serious head injuries following nasty motorbike vs truck smash on Monash this morning.

The collision happened inbound between Springvale & Ferntree Gully Road at Mulgrave about 6.30am.

A man in his 50s has been taken to the Alfred Hospital.

Two lanes on the Monash Freeway are closed inbound from Springvale Road and there are major traffic delays back to Narre Warren.