The Script have described their homecoming Croke Park gig this evening as the pinnacle of their career.
The band, who have just returned from the US leg of their No Sound Without Silence tour, will take to the Croker stage tonight in front of 80,000 screaming fans.
"It feels mental and is the biggest thing we've done," guitarist Mark Sheehan said.
"When The Script kicked off, no one gave a s**t and thought we were American.
"It was tough getting people to come to see us in the Sugar Club. I think we got 63 people there - most of them were family and friends.
"And now to play this place is probably the biggest mind melt."
Playing to an Irish crowd in such an iconic venue has particular resonance for lead singer Danny O'Donoghue, whose dad used to sell sandwiches outside Croke Park.
"We're Irish, we've all been to Croke Park before for massive sporting events," Danny said.
"To sell out in the time we did is amazing."
The band will pay homage to the six students killed in the Berkeley balcony collapse.
"We're talking about it," Danny said.
"Our sympathies are with their families and friends, obviously - we're just watching it on the news coming in. It's heartbreaking.
The band have described this evening's show as their "most interactive to date".
"It's about giving the people with tickets at the back a good show as well," said Danny. "A lot of things we're doing will be a first for Croke Park."
For those unable to get tickets, the band have teamed up with Livestream to broadcast the gig to their fans worldwide.
"It's not the same as being at the concert, but it allows people who didn't get tickets to watch it," said Danny.
Selfie sticks, large cameras and glow sticks are banned from the gig.