It’s difficult to determine how to view the first quarter of Game 1 of the Celtics-Hawks playoff series. The Celtics were pathetic in that quarter, or maybe apathetic is a better word.

They allowed 31 points, 54.5 percent shooting, and trailed by as many as 17 points.

Since then, the Hawks have made just 35 percent of their shots in seven quarters, stifled by a Boston defense that has full respect for the opponent.

And pay no mind to those barbs between Kevin Garnett and Ivan Johnson. Johnson started the exchange by calling Garnett a “dirty player,’’ and Garnett responded by calling Johnson a “nobody,’’ the same term he used to describe Atlanta’s Jeff Teague after he screamed in the face of Ray Allen following a dunk in a March 21 game at Philips Arena.

Don’t be fooled by such language. As the years have progressed and bodies have slowed, the Big Three have had to acknowledge the presence of younger, more athletic, and less intimated players, and pay them respect.

While arrogance and bravado are two reasons the Celtics veterans have remained relevant in today’s NBA - deep into their 30s - Paul Pierce and Kevin Garnett have begun to reveal a higher regard for their opponents.

That is something that Hawks didn’t do in Game 2, when they failed to capitalize on the absence of Rajon Rondo and Allen and blew an 11-point third-quarter lead. They hardly expected Pierce and Garnett to catapult the Celtics past their younger opposition.

It’s that type of disrespect that can cost teams playoff series, and the Celtics have a serious hurdle to avoid in preparation for Friday’s Game 3 at TD Garden.

Atlanta forward Josh Smith may not play because of a strained left knee tendon - the injury that forced him to leave Game 2 with 4:20 remaining.