SMI / Mark Goldman/Icon SMI

WALTHAM — Paul Pierce and the rest of the Boston Celtics know what they’re getting into when they tip off an Eastern Conference semifinal series tonight against the Cleveland Cavaliers.

The Celtics are going to see a steady diet of LeBron James. As in see LeBron shoot, see Lebron pass, see LeBron dunk, see Lebron rebound. James, quite simply, does it all for the Cavaliers.

“He’s arguably the best player in the NBA,” said Pierce.

That argument probably begins and ends with Kobe Bryant. James, a 6-foot-8 guard, led the NBA in scoring this season with 30 points per game. He also averaged 7.9 rebounds and 7.2 assists and beats teams with a scoring-passing panache not seen in the NBA since Magic Johnson engineered Showtime in Los Angeles. The Lakers’ Bryant is expected to be named the league’s MVP and New Orleans’ Chris Paul has burst onto the scene as the next great point guard but James may be feared more than anyone.

He’s certainly the toughest opponent to plan for. In three games against the Celts (2-1 record) this season, James averaged 32.3 points, 9.7 assists and 7 rebounds. James is coming into Boston red-hot. In a series-clinching win over the Washington Wizards last Friday, James went for 27 points, 13 assists and 13 rebounds.

No one defender can deal with James. He handles the ball the bulk of the time and owns a quick, powerful first step that allows him to penetrate the lane almost at will. Double-teams are risky. No big man since Magic can pass like LeBron, and he’ll work his way to the offensive boards if he’s not boxed out.

“One guy is not going to stop LeBron,” said Pierce. “Hey, it’s plain and simple. One-on-one he’s one of the most difficult guys in the world to stop.”

It looks like Pierce will get first crack at James. Also look for Ray Allen and James Posey off the bench to be the Celtics’ second line of defense. Kevin Garnett, the NBA’s Defensive Player of the Year, is bound to face a few midair meetings with James.

Pierce isn’t known for his defense, but he’s the only Celtic who appears physically capable of keeping James under wraps. But the possibility of foul trouble will cause coach Doc Rivers to limit Pierce’s minutes on James.

“What I’m trying to do is just lower his field-goal percentage,” Pierce said. “You don’t want a guy to go for 30 points and shoot 60, 70 percent from the field. I definitely have my work cut out for me. It sounds easy to talk about, but those are the things we have to do to go out and win a series.”

Pierce prides himself on his ability to use his body to overpower opposing players both with his own offensive game and also defensively. That strength is nullified against James.

“There’s probably one or two guys in the league where I have to say, ‘Hey, this guy is more physical than I am.’ I’d have to say Ron Artest and maybe Carmelo Anthony [are the others besides James],” he said.

James may be as multi-dimensional as any player in the NBA, but he has plenty of help, too. A midseason trade brought former Celtics Delonte West and Wally Szczerbiak to the Cavaliers’ backcourt. They and second-year guard Daniel Gibson have hit huge shots in the playoffs. The trade also improved Cleveland’s defense with rebounder-shot blocker Ben Wallace coming on board to help 7-foot-3 center Zydrunas Ilgauskas hit the boards.

With options inside and out, James gets his 30 points and also sets up teammates for open shots.

“Once he gets the ball, their offense starts,” said Rivers. “You don’t know where he’s going. You just want to force him to certain spots on the floor.”

At just 23 years old, James is the fastest player in league history to score more than 10,000 points. He’s already the Cavaliers all-time leading scorer and is just getting harder to stop.

“The obvious thing is he’s shooting the ball a lot better than he has in the past,” said Pierce. “He’s finding his teammates even more than ever. He’s doing a great job of just mixing it up.”

kmcnamar@projo.com