With Banner 18 in reach, Celtics fans aren’t letting anything dampen their spirits.

Fans gathered outside TD Garden hours before the arena opened for its Game 4 watch party, anxiously waiting to get inside — knowing what the night ahead could bring.

About 1,200 fans who didn’t get tickets to the sold-out Garden watch party flocked through the doors of Big Night Live, right outside the arena, for festivities there.

“Let the haters hate, let the birds chirp,” said Celtics superfan Brian Babz, organizer of the Big Night Live watch party. “At the end of the day, the Boston Celtics have a chance to sweep. They’re getting compared to the 1980s Celtics. We’re witnessing greatness.”

Babz and his friend KJ Green, who flew to Dallas Friday morning to take in Game 4 live, have organized watch parties at Big Night Live since the 2022 playoff run. Friday night’s party drew the largest crowd to date, Babz said.

“Everybody wants to be here for a clincher,” he said. “It’s a Friday night in Boston. The vibes are going to be immaculate.”

Inside the Garden, loud cheers roared when the jumbotron showed Jaylen Brown and Kristaps Porzingis arriving at the American Airlines Arena, about 1,700 miles away. Boos wrung out for former Celtic Kyrie Irving, the same treatment the now Maverick has received throughout the series.

Ahead of Game 3, Garden officials removed floor seating and placed a large stage in the corner for Celtics dancers and Lucky the Leprechaun. The Game 4 watch party features a different layout, with a majority of floor seating back.

New Hampshire resident Christopher Soldani arrived at the Garden at 11 a.m. Friday after a two-hour commute through traffic from the Seacoast. He has become known as the ‘Cape Man on Causeway,’ as he’s worn a large green cape with player names and numbers attached throughout the Finals.

“It would mean everything in the world,” Soldani told the Herald. “It would mean everything to these fans – to give us hope between John Henry not wanting to sell the Red Sox, the new era over at Gillette Stadium.”

Worcester resident Alex Reyes is already thinking about how sweet another championship parade would be through the streets of Boston. The last time duck boats made their way through the city for a parade came over five years ago after the Patriots won their sixth Super Bowl.

“It has been 16 years since we won one,” Reyes said. “I didn’t get to go to the other Celtics parade, and that’s the only parade I’ve missed. … Celtics fans are just different, they’re a different breed. We bleed green.”

Boston Police geared up for a potential championship celebration outside of the TD Garden, warning drivers and pedestrians that streets around the arena would shut down at the halftime of Game 4.

In a traffic advisory Friday afternoon, police alerted that Causeway Street from North Washington Street to Merrimac Street will be closed, while all feeder roads off Causeway to New Chardon Street will also shut down, at halftime.

“There will also be no re-entry to any establishments within that area,” the advisory states.

City resident Lisa Viale, dressed in a Dunking outfit, has been a Celtics fan since the days of John Havlicek and Don Nelson. She believes this season’s iteration of the Celtics “represent the city well.”

“They’re all pretty good guys, clutch,” she said of the team. “D White, clutch. Jaylen Brown has been clutch. Jayson Tatum has been taking a lot of heat, but these guys don’t want to lose.”

A Celtics fan holds up a “How Sweep It Is” sign during the Game 4 watch party at the TD Garden (Stuart Cahill/Boston Herald)
Lucky Lou cheers on his team at the Celtics Game 4 watch party at TD Garden (Stuart Cahill/Boston Herald)