"But with many of the games being played in the early hours of the morning, we're reminding those out socialising to think very carefully about their alcohol and fatigue levels if driving - or better still, to make other arrangements for getting home."
Police will be on patrol and setting up checkpoints across the country throughout the Rugby World Cup.
Drivers should expect to be stopped and breath-tested anywhere, any time, Mr Greally said.
Police will also be issuing "yellow cards" to drivers ticketed for any offences that attract demerit points, he said.
"The message is simple - we want to remind those drivers whose behaviour has resulted in demerit points that they risk getting 'sidelined' if they keep driving in a way that puts others at risk, which can eventually see their license suspended."
Acting Assistant Commissioner Prevention, Superintendent Dave Trappitt, said police will be patrolling through areas where bars and pubs are showing the games live.
"The goal is to reduce alcohol-related harm and make sure the environment is safe for everyone. While we want people to enjoy themselves, we know that alcohol is a major contributor to crime and victimisation, with a significant proportion of all recorded offences committed after the offender has been drinking alcohol," Mr Trappitt said.