The victim - who was hospitalised with a severed Achilles tendon, ligament damage to two fingers, and bone damage to his left leg - managed to fend off some of the attack with a bike tyre as blows were aimed at his head and chest.

Ivan Terrence Torbert, 37, pleaded guilty in the ACT supreme Court on Thursday to recklessly inflicting grievous bodily harm.

Court documents said the violence had been sparked because Torbert believed the man had stolen from him during a trip to Cash Converters on the morning of September 26 last year.

Torbert sent the man a threatening text message warning him to be at his house in a few minutes or "be scared".

The offender then tracked the man to a Watson flat, where he launched the attack from behind and without warning.

The first swing of the blade severed the man's right achilles tendon.

The victim fell to the ground and turned to see Torbert standing with the weapon raised at head height and yelling "you're finished".

The victim then used a bike tyre to fend off several blows before his two dogs came to his aid.

The victim began to stand when Torbert struck him in the leg , below the knee, with enough force to severe a tendon at the front of the leg and break off a chunk of bone.

Torbert then fled when neighbours came outside after hearing the noise.

A nurse rendered first aid to stem the bleeding before the authorities arrived.

Torbert initially pleaded not guilty to the offence and had been scheduled to stand trial later this year.

But his switched his plea in the Supreme Court on Thursday.

Chief Justice Helen Murrell remanded Torbert in custody, and ordered presentence and drug and alcohol reports be prepared.

Torbert will reappear before the court for sentencing in August.