Celtics fans descended on the Garden ready to party.

Causeway Street and Hub Hall, attached to the TD Garden, turned into a sea of green and white well ahead of Monday’s Game 5, with some fans crossing their fingers that the Game 4 loss in Dallas was a fluke and others more confident.

“The fans are here. The team is back in Boston,” super fan Christopher Soldani told the Herald. “There’s nothing more in the world that Boston could have. The Celtics are winning.”

Soldani has garnered attention as the “Caveman on Causeway,” as the New Hampshire resident has rocked a beard and a green cape attached with player numbers and names throughout the Finals.

He pointed out how the Celtics have not lost four games in a row in several years. No team in NBA history has ever come back after digging themselves into a 3-0 hole. Soldani doesn’t believe the Mavericks will break that trend.

“Tonight is going to be a hell of a story,” he said.

Getting into the Garden proved daunting. Tickets for Game 5 on Saturday were reportedly the “most expensive ticket in Boston sports history,” according to TickPick, with the cheapest going for $1,715.

But prices dropped marginally an hour ahead of tip-off, with the cheapest listed on StubHub at $963 around 7:30 p.m. The most expensive cost a whopping $13,231 for the third row behind the Celtics bench.

Celebrities attending the potential championship clincher include Jack Harlow, Donnie Wahlberg, Maria Menounos, Camille Kostek, and former Celtics’ ML Carr, Leon Powe and others.

For 400 fans who couldn’t get into the Garden, they flooded Big Night Live, next to the arena, for a sold-out watch party.

By coincidence, Russell Espinosa, a longtime Celtics fan, flew to Boston with his wife and son Marcus for a youth travel baseball tournament this coming weekend. The family from Fresno, Calif., planned on watching the game at a nearby restaurant.

Espinosa said watching the Celtics fall to Golden State in the 2022 Finals was hard, especially while surrounded by Warriors fans. If Boston pulls it out Monday, he said he and his family would attend the championship parade later this week.

“Being from California, there are so many Lakers fans,” Espinosa said. “Getting that 18th banner over their 17 – it would be perfect.”

His son Marcus added, “I’ve always wanted to come to Boston to watch the Celtics play. It would be amazing, really, really cool.”

Boston Police earlier Monday warned pedestrians and drivers that Causeway Street and all feeder streets between Causeway and New Chardon Street would shut down to traffic after the first quarter.

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

Katie McGowan, who lives around the corner from the Garden, called the Celtics on the verge of winning Banner 18 “magical.” She attended Game 2 105-98 victory, and the team’s cohesion stood out to her.

“This place is going to erupt,” McGowan said of the Celtics potentially sealing the deal. “We’ve been looking at this for years, almost getting there. But maybe this year they’re going to win as a team, and it’s not just one guy. People will step up at different times, and that’s what is most special about it.”

Rick Rossetti and his daughter Kara of Somerville were ready for action ahead of Game 5. (Nancy Lane/Boston Herald)
A sea of green stretches out on Causeway Street ahead of the Celtics Game 5 match up against the Mavs last night. (Nancy Lane/Boston Herald)