Celtics fans are always up for a challenge.

The loud, energetic crowd that saw Boston take Game 1 of the NBA Finals in convincing fashion over the Mavericks didn’t fully meet Jaylen Brown’s expectations, the Celtics star told the media on Saturday.

“I thought the crowd was good,” Brown said. “I think we can be a little bit better. I expect us to be even louder. Sunday, we are going to need our fans to be hyped. It’s not just team versus team. It’s crowd versus crowd. It’s gas station versus gas station. Supermarket versus supermarket. It’s the whole city versus the whole city. We need everybody.”

As tip-off of Game 2 drew closer, Celtics fans flooded Causeway Street, eager to get into the TD Garden with hopes of watching their hometown team take a commanding 2-0 lead in the series.

“Long story short, the energy is coming tonight. The energy is coming tonight,” Corey Decker, of West Springfield, told the Herald, rocking a Jayson Tatum jersey.

Boisterous “Let’s Go Celtics” chants wrung out around 5:30 when legend Paul Pierce and a set of superfans appeared from a window at Big Night Live, pumping the crowd up with adrenaline for the night ahead.

Brown has challenged the Garden crowd in the past.

After Boston tied up the Eastern Conference Semifinals against Philadelphia last year, forcing a Game 7 at the Garden, Brown had a message for fans: “Energy in the Garden has been OK at best all playoffs. Game 7, if you’re there or if you’re not there, if you’re watching at a bar, if you’re watching down the street at a friend’s house, I don’t care. I need you to be up, I need you to come with the energy.”

Tatum then delivered a Game 7 masterpiece, dropping 51 points while grabbing 13 rebounds, to power the Celtics past the 76ers.

“I called the Garden out in the last game and, way to respond,” Brown later told reporters. “The energy in the building was through the roof. It was amazing.”

Matthew Pescitelli, attending Game 2 with Decker, blamed the public address system for making it hard for fans to be as loud as they want.

“I would love to do chants every single possession, but they facilitate the chants,” he said of the PA system. “I want to make a difference.”

Decked out in Derrick White gear, Patty Stowe, of Brunswick, Maine, said she felt “overwhelmed with excitement,” calling herself a “nervous wreck,” as Game 2 approached.

Sunday marked the first time Stowe attended the Finals.

“The passion and enthusiasm and just the overwhelming hunger to win this,” Stowe said of what makes this team different in the past. “I’ve never seen a team this jacked up to win this.”

Among the sea of green, a healthy dose of blue and white stood out as Mavericks tried to make their presence felt.

The Game 1 loss has not deterred the confidence of Nick Remete, who drove down from New Brunswick, Canada with his friend Ryan Whittaker, a Celtics fan, Sunday morning.

Remete, who started following the Mavericks because of legend Dirk Nowitzki, said he expected Dallas to claw back and a potential 50-point performance from current superstar Luca Doncic who was listed questionable before Sunday’s tilt.

“They’re going to come back with a vengeance,” Remete said. “Boston has some complacency when they go up too big. They’re going to learn their lesson tonight.”

Chris Almaguer flew out from Oregon to capture the game with his nephew Nathan.

Almaguer said he was hoping for a better performance from former Celtic Kyrie Irving who had lost 11 straight at the Garden, before Sunday, since he infamously stomped on the Lucky logo on center court after defeating Boston with Brooklyn in May 2021.

“I hope I don’t get too much crap but I know I will,” Almaguer said about wearing a Mavericks jersey inside the Garden.

His nephew called the experience a dream.

“I’ve always dreamed of coming here,” Nathan Almaguer said. “It’s nice to see other Celtics fans because where I’m from, there are hardly any Celtics fans. It’s nice to be in an environment where I’m on the home team.”

Paul Pierce gets fans riled up for another ring before Game 2 of the NBA Finals at the TD Garden . (Nancy Lane/Boston Herald)