Conor McGregor has called on the Irish military to be deployed, so they can help enforce the country's lockdown.
On Friday night, the Irish government told people to stay at home for two weeks, in a bid to contain the spread of coronavirus.
And UFC star McGregor says the police will need help ensuring people stick to it.
In a video posted on Facebook, he said: "If you do not enter the game, you cannot win it.
"We have now entered the game and, with strict adherence to the methods, we will win.
"We must abide by this and I pray for the health of the country that we do so.
"We cannot go by chance here.
"I urge our government to utilise our defence forces.
"Our defence forces have been mentioned as a possibility in assisting our 15,000 available Gardai (Police) but only if necessary. However, it is necessary.
"Any less than full adherence to these newly put-forth methods by any member of our society will not only be a mockery to what we are attempting to do - it would put the rest of our great nation in danger.
"You are doing your country an incredible deed by staying put."
Taoiseach Leo Varadkar says people in Ireland should stay at home until at least 12 April - unless they are buying groceries, attending medical appointments or collecting medication, getting brief exercise or making essential family visits.
Almost all shops have been told to close and all gatherings outside of families have been banned.