BOSTON — A sea of green-clad Celtics fans entered the TD Banknorth Garden last night with a swagger not seen around here in a long time.

Up the front escalator came Bill LaGrange, a 20-year-old from Derry, N.H.. He spotted a silent auction table set up next to the entrance offering Celtics collectibles, and some signed by the visiting Cleveland Cavaliers and their star, LeBron James.

On this night, Celtics fans puffed out their chests, and reminded the rest of the league that the Celtics were back.

“Is that a LeBron jersey? I’ll give you five bucks for it,” LaGrange yelled to the auctioneers, as his friends hollered alongside him.

Then he saw the signed Kevin Garnett jersey. His eyes went wide, and he yelled into the packed corridor.

“I will pay $1,200 for that right now. Who do I have to talk to?” he hollered.

For the first time in more than a decade, the Celtics began a season as the hottest ticket in the nation’s hottest sports town. Last night, the Celtics began their championship defense against the Cavs, and raised to the rafters the 17th banner in the franchise’s history.

Into the Garden poured the fans of an enviedchampionship team: a rowdy mélange of bandwagon fans, die-hards, and the simply lucky, like Paul Pavidis and Johnny Santos of Lowell, Mass., who won tickets to the game on a Jamn’ 94.5 radio giveaway.

“Luck of the Irish, I guess,” joked Pavidis, 23, as he and Santos double-fisted pregame beers in The Hub, a Garden bar.

Most weren’t so fortunate. LaGrange and his friend, Keene State College student Dean Germinara, each had paid $300 for their tickets, but they had vowed there was no way they were watching the opener on television.

“I missed class today. I’ll miss class tomorrow. Last June, I said there’s no way I’m not going to the opening game,” said Germinara, who came to the Garden in a blue, $325 Farragut Academy High jersey, Garnett’s alma mater.

The stands were packed an hour before the game for the opening ceremony, where Celtics players were given their massive championship rings. They were set with emerald shamrocks and 64 diamonds, the words “Banner 17” running down one shank, the team mantra, “Ubuntu,” running down the other.

The jewelry is tangible recognition of what the fans made clear all night: for the first time in years, the Celtics are equals to Boston’s other millennium-era sports royalty, the Red Sox and the Patriots. The crowd cheered during nearly the entire national anthem. It shrieked as the image of late Celtics patriarch Red Auerbach appeared on the Jumbotron. It chanted “Let’s Go Celtics!” as they watched video of Coach Doc Rivers drenched in Gatorade.

It was a playoff atmosphere before the Celtics even played a minute of basketball.

The noise reached its peak when Celtics captain Paul Pierce reached the floor and took the championship trophy in his hands. Pierce, a grown man standing amongst 19,000 strangers, was in tears for nearly the entire ceremony.

As the players were introduced one by one, wires descended from the ceiling. Team staffers attached them to a large piece of cloth lying on the floor. When the introductions finished with MVP chants for both Garnett and Pierce, the wires pulled taut, and the banner began to rise from the ground.

“Ladies and gentlemen, it is now time to raise an unprecedented 17th banner to the rafters,” the announcer stated simply, and the players tugged on a pulley that brought the banner in line with the 16 others.

Pierce took the microphone towards the end of the celebration, and thanked everyone from his high school coach to, of course, his mother.

“As a kid, I always dreamed of moments like this,” Pierce told the cheering crowd. “You never know if this day is going to come, and I had my dream come true, to hang a banner in the rafters.”

For many in the crowd, the moment rivaled winning the championship itself. Four-year season- ticketholder Luke Lomartire, 31, brought his uncle, Robert McGann, 54, of Waltham, as a thank-you for raising him as a Celtics fan. The two attended numerous big games together in the Celtics 1980s glory days, but last night was unique.

“It’s ironically the first game of the season, and the biggest ticket of the season by far. It instantly became that when they won [the championship],” McGann said.

The crowd pulsed around them, and Lomartire marveled at the vibe.

“It’s like a playoff game that they’ve already won,” he said.

They reminisced over long-ago games against the Lakers, and over Larry Bird Day, and then McGann made a proclamation.

“This is our greatest Celtics moment together,” McGann said, clutching his nephew’s shoulder.

dbarbari@projo.com