LAS VEGAS — On the eve of Team USA training camp, Boston Celtics teammates Marcus Smart, Jaylen Brown, and Jayson Tatum were photographed walking side-by-side into a team meeting at their Las Vegas hotel.

The snapshot, showing the three players with wide smiles on their faces as they chatted while walking ahead of other campers, immediately became the poster for this Team USA experience. Playfully dubbed Team Shamrock by Smart, the Celtics are here in Vegas not only to represent their country on a global stage but to lay the foundation upon which they hope their own Redeem Team will be built next season.

"That [photo] wasn’t planned at all, by the way,” Smart said after Team USA’s first workout Monday on the campus of UNLV.

Yes, it seems these Celtics are just sorta gravitating towards each other now. Which is why, when their Team USA chores were complete on Sunday night, the trio of returning Celtics and newcomer Kemba Walker all ventured out to dinner together on the Vegas strip in hopes of building the chemistry that these players believe will be vital to the team’s overall success — particularly coming off the train wreck that was last season.

"We talked a little bit about basketball, nothing crazy, but really just knowing each other’s personality,” Smart said of the Team Shamrock dinner.

Added Brown: "It was fun. We got some good guys here, so we’re starting to build that chemistry early. Hanging out with Kemba, seeing what he’s like.”

Just how important is that chemistry for this year’s group?

"It’s huge,” said Smart. "Everybody knows that championship teams… or really great teams, they have a certain oomph to them, where you look at them and you’re like, ‘Those guys, they’ve been together for a while,’ or, ‘Those guys really know how to play well with one another.’ That’s all we’re trying to build.”

Walker spent much of Day 1 of training camp with a grin on his face, even as he showed some summer rust on his handles. There were some intriguing glimpses, like when he exploded to the basket for an and-1 layup late during an intrasquad scrimmage. But he missed a potential scrimmage-tying 3-pointer for the blue team at the buzzer — with Brown defending — as the white squad squeaked out a win (Brown promptly declared bragging rights over his teammates).

But Walker is clearly smitten to get to know his new teammates — with Team USA but especially with the Celtics.

“It was fun. Fun to be out there with those [Celtics] guys,” said Walker. "Those guys are super cool, fun to be around. I’m enjoying my time with them.”

Walker then reaffirmed how players like Tatum and Brown played heavily into his decision to sign in Boston. He noted how he talked to Tatum in Paris and Brown the year before in South Africa. He didn’t know Smart as well but gushed about him Monday while noting, "He’s one of those guys that you want to have on your team, or you have to have on your team.”

To be sure, there is always good vibes this time of year. And yet it’s hard to ignore the positivity around the Celtics this summer. This doesn’t feel like a team that saw two All-Stars depart for Eastern Conference rivals. There’s a genuine air of excitement about what lies ahead.

The Celtics have not shied away from admitting that last year did not go as anyone expected. Boston players have routinely taken the high road and not pinned their struggles on any one player and most insist the team simply never clicked.

Asked about the good vibes this summer, Brown’s response was particularly notable.

"It can only be positive. Last year, I can’t see it being any worse than that,” said Brown. "Coming out and being positive is everybody’s mindset.”

Pressed on the dysfunction that Smart had already admitted existed earlier this summer, Brown had no desire to look in the rearview mirror.

"I don’t really want to get into the logistics and talking about it,” said Brown. "It was dysfunctional, yes, but it’s over with now. I’m here with USA Basketball, I’m looking forward to what’s to come next, and we’ll see how the ball rolls.”

Long after practice had ended, Brown and Tatum remained on one of the practice courts inside the Mendenhall Center playing a rotating game of 1-on-1 that also featured Miami’s Bam Adebayo. The buzzer blew loudly twice after the allotted 30 minutes of media access time expired and Team USA coach Gregg Popovich playfully stomped onto the court to fetch Brown as reporters were peppering him with final questions long after the buzzer.

Popovich threw his arm around a smiling Brown and the two walked off together. When Walker burst through the side doors soon after, the fans waiting in the 112-degree for an autograph or a selfie roared for his arrival. Even more smiles. 

Yup, that’s been the theme of this trip so far.

"Very excited. Very excited [about next season],” said Brown. "I’m looking forward to it. We’ll see what happens but I’m excited. I’m really [trying to be] positive, not thinking about anything negative. Just coming forward and trying to be the best version of Celtics basketball.”

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