Mr Groet, 27, is one of three flatmates who live at a property on Waipa St, Birkenhead, on the North Shore.
Police were called just after 10am yesterday after Mr Groet chased the two would-be burglars out of their home.
"I managed to get a punch in there, on one of them ..."
The man who entered his room had a ski mask on top of his head. On seeing Mr Groet, the burglar snapped it down, covering his face.
The pair got away in a stolen car, found abandoned on Seaview Rd, Glenfield, a short time later.
Despite police being called and an Eagle helicopter searching the area, the offenders got away.
It wasn't until afterwards Mr Groet thought about how badly the situation could have turned out.
"I didn't think about it at the time ... And your first thought, anyway, is that there's someone in your house and to chase them out."
The incident comes after a vehicle was stolen from the flatmates' home on Saturday.
"They would've had the house keys and they must've thought we were all at work," Mr Groet said.
They have since had locks in the house changed.
• The offenders are described as being in their late teens to early 20s. One is of slim to average build and both are of Maori or Pacific descent.
Anyone with info can call Police or CrimeStoppers: 0800 555 111