Two men jailed over an unprovoked Geelong bashing three years ago have had their sentence reduced.

Michael Tancredi, an aspiring V8 Supercar driver, was sentenced last year in Geelong County Court to four years' jail with a minimum of two years and eight months, while Andrew Pamvouxoglou was imprisoned for three years with a non-parole period of two years after both pleaded guilty to recklessly causing serious injury in relation to the assault on June 15, 2007.

They appealed their sentence on the ground that sentencing judge Anthony Howard had erred in reasoning that they did not foresee the full consequences of their actions - namely the serious brain injury that victim Nathan Cafaro suffered.

They also argued that their sentences were manifestly excessive.

Court of Appeal justices David Ashley, Robert Redlich and Robert Osborn agreed and handed down their reasons this morning.

The sentencing judge had heard that Tancredi kicked a drunk Mr Cafaro in the chest and punched his jaw "so hard and effectively that he collapsed onto the pavement" after Mr Cafaro kicked an empty can in their direction and then punched a phone box as they walked past him as he waited for a cab at 1.20am in Moorabool Street.

Pamvouxoglou then kicked Mr Cafaro twice to his upper body as he lay on the ground in the foetal position.

A witness testified that the pair were "clearly hitting a person who was not able to fight back".

The men left Mr Cafaro bleeding and unconscious at the scene. They later returned to where the assault took place to find an ambulance and police present, but again drove off.

Justice Howard described the impact on Mr Cafaro as "horrendous". He required emergency surgery for a serious brain injury and endured six months of rehabilitation but has since fully recovered with no permanent brain damage.

The men handed themselves into police the following week.

The Court of Appeal judges found that "the appellants should be treated as having had foresight of serious injury, but not brain injury of the gravity actually sustained by the victim".

They ordered Pamvouxoglou to serve two years' jail with a non-parole period of 14 months and Tancredi to serve three years with a non-parole period of two years.