Those heading to the All Ireland hurling final today are being advised that all trains from Cork and Limerick to Dublin are sold out.
40,000 hurling fans will travel to Croke Park today for the match - the largest crowd at a sport event since the pandemic began.
However, current COVID-19 restrictions mean trains are currently running at only 75% capacity.
Irish Rail says pre-booking tickets is mandatory and no tickets will be available to buy at stations.
Spokesperson Barry Kenny says all trains are sold out - including evening services after the match.
He said: “If you don’t already have a ticket, there will not be tickets available at the station - you won’t be able to board without a pre-booked ticket.
“Those who have been lucky enough to book their train in advance, you must travel on the specific train you have booked.
“For people who perhaps aren’t travelling for match purposes or were hoping to travel for other reasons… unfortunately no trains to Cork, Kerry or Limerick out of Dublin this evening will have any availability.”
Meanwhile, the Lord Mayor of Limerick says it's the reality there will be a rise in COVID-19 cases after today's All Ireland Hurling Final.
The match comes amid the ongoing Delta wave of the virus.
The HSE this week urged supporters to limit their social activity after the match, asking those gathering for the final to be mindful of the public health guidelines.
Daniel Butler, councillor and Lord Mayor of Limerick City and County, says people need to try and reduce the risk of spreading the virus.
He said: “We’ve seen it elsewhere across Europe… the reality is there is going to be an increase in cases.
“That’s a reality we have to accept. What we’re trying to do is reduce the potential damage that may be done… to an absolute minimum.”