By Matthew Geagan, CBS Boston

BOSTON (CBS) — The Celtics just gutted out a hard-fought seven game series against the Washington Wizards to move on to the Eastern Conference Finals for the first time since 2012.

It’s a great accomplishment for head coach Brad Stevens, mastermind Danny Ainge and the entire roster of castoffs and young players, and there’s little doubt that the future is bright in Boston.

At least big picture-wise, the future is bright. The immediate future is a different story. The C’s prize for living up to the preseason expectations and making it to the Conference Finals is a showdown with the defending champion Cleveland Cavaliers, who are 8-0 this postseason and have been sitting and awaiting their next victim opponent for over a week.

The Cavs took three of the four matchups with the Celtics during the regular season, and the last one left a sour taste. Cleveland had been stumbling a bit with the regular season winding down, while Boston was playing some of their best basketball. Then LeBron and company came in on April 5 and stomped the C’s on their home floor, 114-91, with James doing whatever he wanted. Most of Cleveland’s star players played well into the fourth quarter despite the lopsided score.

Cleveland sent a message with that win: the Celtics may be on the rise, but they still have a giant mountain to scale.

That will be the case when these two battle for a spot in the NBA Finals, with the odds greatly against the Celtics. But that’s the way they’ve liked it since Ainge brought Isaiah Thomas on board, and this C’s team is eager to try to once again prove they are closer to the Cavs than most would assume. And like the Cavs send a message just over a month ago, the Celtics should try to do the same over the next two week. Not one that they’re there, but one that they’re coming, whether that is next year or a few years from now.

We’ll see if they can do just that over the next 4-7 games. Here’s what we’ll be watching for when the series tips off Wednesday night at 8:30pm:

On Guard!

LeBron James (Photo by Jason Miller/Getty Images)

LeBron is the best player in the NBA and he’s looked even better during the playoffs, averaging 34.4 points per game. He’s shooting 56 percent from the field and an absurd 47 percent on his three-point bids.

When he wants to get to the hoop, James is going to get there (or the free throw line, at a frustrating pace). He’ll beat you as the leading scorer or as the quarterback of a well-oiled offensive machine. He’s really, really, really good, and he loves to play against the Celtics, averaging 29.6 points over 46 career games against Boston.

There’s no real way to stop him, so slowing James down is as good as it’s going to get. It’s going to take a mix of everyone to do so, from Jae Crowder to Marcus Smart to maybe even some Jaylen Brown. If the Celtics are lucky, one of those three can take James off his game, even just for a few minutes on a given night.

But then there is his band of merry men with the likes of Kyrie Irving, Kyle Korver, Kevin Love and J.R. Smith, who can all knock down shots. In total, there are eight regulars on the Cavaliers shooting 40 percent or better from beyond the arc.

Avery Bradley will probably spend most of his time on Irving, who is not one of those Cavalier regulars shooting well from downtown (he’s at just 28 percent with seven attempts per game). Still, guarding him is no walk in the park, and trying to keep him in check on the offensive end will likely take a little bit off of Bradley’s own attack. It’s a difficult balance, and part of what makes the Cavaliers so darn good, but those offensive-defensive matchups are also one of most interesting parts of the series.

A sack on James and his Eastern Conference kingdom could be coming soon, but not yet, and not by this Celtics team. We’ll see if the Celtics can take those first steps, however small, in laying that groundwork this series.

Big Al’s Big Moment

Al Horford. (Photo by Maddie Meyer/Getty Images)

Chances are Isaiah Thomas is going to do something special during the series; it’s what we now expect from the little guy. But he couldn’t do it all on his lonesome in the first two series against the Bulls and Wizards, and he sure as heck won’t be able to do it all against the Cavaliers.

That’s where Al Horford comes in. The big man has been everything the Celtics wanted and a little more this postseason, and while Thomas may be their scoring leader on a nightly basis, it’s Horford who is their overall leader (and best player) as they head into their toughest matchup.

Horford averaged just nine points, six rebounds and 4.7 assists in his three games against the Cavs during the regular season, but has been one a whole new level this postseason. Forget the 16.1/7.5/5.8 stat line — that is great in its own right. But Horford is hitting 64 percent of his shots from the floor, and 58 percent from downtown. LeBron’s shooting has been spectacular this season, but Horford’s has been downright absurd.

Horford is that silent assassin who, every night, does two dozen things to help the team. Whether it’s knocking down shots, setting screens to spring Thomas or stretching the floor so that little man has room to move among some trees, Horford gets it done.

Now we get to see if he can continue that stellar play against the top-tier of the league.

Turnovers Will Be Even More Costly

Marcus Smart put it best after Monday night’s Game 7 win when telling reporters when it would take to beat the Cavaliers: “Perfection.”

Not giving a team free possessions is always a key in any series, but it’s a whole new level with the Cavaliers. Turn the ball over against them and there’s a good chance it’s going to end in some highlight reel dunk that ESPN will show 4,000 times with some horrible emo rock playing in the background (if they can make time for a highlight, that is).

In their four-game sweep of Toronto, the Cavaliers turned 33 Raptors turnovers into 47 points. They went Globe Trotters on one of them early in Game 1 (see the video above) and it essentially ended the series before the Cavs had to dust off their passports. They toyed with the Raptors the rest of the way, whether LeBron was pretending to drink a beer or spinning the ball before putting up a shot (if he pulls that on the Celtics, just take the ball!).

Turnovers were one of Boston’s biggest detractors in their losses in Games 3 and 4 against the Wizards, and they were a big part of why Washington was able to go off on those ridiculous 22-0 and 26-0 runs. If they make the same lazy miscues in this series, forget about putting up a fight against Cleveland.

Take One Game In Boston, And See Where The Rest Goes

Celtics guard Isaiah Thomas reacts during Game 5 against the Washington Wizards. (Photo by Maddie Meyer/Getty Images)

If the Celtics want any microcosm of a chance to make some noise this series, they have to take at least one game in Boston. They need to take advantage of Cleveland’s lengthy layover between their sweep of the Raptors and press them as much as possible when Game 1 tips off. They have to be ready to throw the first punch.

And we don’t mean a rematch of the Kelly Olynyk-Kevin Love shoulder wrestling showdown. Though that might be fun.

The Celtics are only expected to win a game or two, if that, during this series, and that would be considered a win for the young underdogs. It’s incredible that “just winning a game or two” or “just keeping it competitive” would be considered a success for a team that resides in the “City of Champions,” a team that has a history like no other in NBA. But that’s how good the Cavaliers are, and how big the gap is between the them and the Celtics.

That’s really no knock on the Celtics, who are a bit ahead of schedule in their rebuild. And don’t think for a minute that just because most logical fans have accepted the fact the Celtics will probably only be playing four or five more games this season, that the team themselves are just going to lay down and let the Cavs march on to the NBA Finals without a fight. They are going to battle for 48 minutes every night, making Cleveland earn a trip to their third straight Finals.

There will be demoralizing Cleveland runs. The Celtics will answer some, others they won’t. But they won’t quit, no matter how high the mountain. That’s really all you can ask for when a promising underdog goes against a Goliath like the Cavaliers.