ISTANBUL — The wonders of Istanbul beckon, and Jeff Green is sure that he'll spend time gazing up at the heavenly dome of Aya Sophia and maybe even the radiant tiles of The Blue Mosque.

But the Celtics forward isn't too concerned, because it's not basketball. For a player trying to finally fit in with the team he joined in the spring of 2011, ancient architecture isn't all that important.

“Whatever the tour guy says is the most popular, I guess. Find a tour guide, take my camera and take pictures,” Green said of sightseeing interests after Wednesday's practice. “It depends on how my body feels. The most important thing is this game we have (tomorrow), and if I'm fatigued and tired, I'll take my rest in my room.”

He'll probably spend that time contemplating moments such as Wednesday, when his hesitancy with the ball led to a mild lecture by Doc Rivers from a timeout. The Celtics coach, who is trying to unlock the secret to Green's obvious talent, had a simple message. Shoot or drive. Do something.

Green quietly leaned against the scorer's table and absorbed the critique. His goal is to move on from this, to finally fit in.

“It's been great being under Doc from the start, and having these guys around me and me knowing their games and them knowing me a little bit more,” he said of coming back from a lost season. “It's all coming along and hopefully it continues. I don't have to figure out how to fit in. The more we play together, the more we learn. It allows (Rajon) Rondo, Paul (Pierce), Kevin (Garnett) and myself to know where guys like it.

“It was tough (two years ago). You come into a situation where a group of guys have been together for five years. You're stepping into unfamiliar territory. Things didn't quite work out as everybody planned, but now is better.”

Green played the last 35 games of the 2010-11 season as a Celtic, including nine in the playoffs.

Last year's unfortunate hiatus for heart surgery considered, he remains a puzzle — a talented combo forward whose true value has yet to be discovered by the coaching staff. All too often in the spring of 2011, Green was caught in between as Rivers strained to determine his value at small forward and power forward.

Now, in Green's first Celtics training camp, Rivers can see the respective benefit. Green is a power player against small forwards. With his speed, Green should be a matchup dilemma for most so-called 4's. As Rivers has said, there aren't many power forwards comfortable guarding him on the break, especially when Rondo is pushing the ball.

So the promise is there. At 6-foot-8 and 235 pounds, Green is actually bigger than starting power forward Brandon Bass. And he's capable of scoring at the rate of his relief on the other side, Pierce.

“He's a guy that makes our lineup so much more versatile, because he can switch from the 3 to the 4, or he can give us a big lineup with him at the 3 and me at the 2,” said Pierce. “He'll be a big key for us, but the pressure's not on him because it has to come from a combination of guys off the bench -- Jason (Terry), Chris Wilcox, (Jared) Sullinger. So it has to be a number of guys.”

But Green has been special in the past, and there is genuine hope that with more familiarity comes a jump in his game. The support network is there, as Green knows.

“I don't think we've seen the best of Jeff. J-Green has a lot of skill, man,” said Garnett. “There's times where, like all of us, he thinks a lot. He's no different. But you see his skill, you see that confidence coming. It's a process, but you kind of marvel at how good he is. No, I don't think we've tapped into that resource yet.”

No one doubts, though, the value of that resource.

“That's on Doc,” said Garnett. “Doc's system is what it is. We don't put ourselves in the game and give ourselves roles. But he gives us opportunities to be aggressive. Jeff just has to take his opportunities when he has them. But he looks good.”

mrmurphy@bostonherald.com