Our NBA experts answer the big questions and make predictions for this Eastern Conference finals matchup.
1. What are you most excited to watch in this series?
Brian Windhorst, ESPN.com: You're always excited to watch LeBron. Some of the most pivotal games of his career have come against the Celtics in the playoffs, especially at TD Garden; some of his highest highs and lowest lows have happened in that concrete box with its yellow and brown seats. I'm ready for the next chapter.
Kevin Arnovitz, ESPN.com: Cleveland has an all-purpose forward who dictates the terms of the game every time out. Watch him play and you'll see a player who combines size and speed, power and finesse, creative playmaking and incomprehensible shotmaking. The really crazy thing? James has played nearly 3,500 minutes since opening night.
André Snellings, ESPN Fantasy: Boston faced three phenoms in the first two rounds of the playoffs and did well containing Giannis Antetokounmpo, Ben Simmons and Joel Embiid. I want to see how the Celtics match up with the ultimate phenom, James, and whether their young players can continue their fearless performances when facing the best player in the world. If Jayson Tatum, Jaylen Brown and Terry Rozier can look "Thanos" directly in the eye and continue to play their best ball, then we'll know these young guys are truly special.
Jeremias Engelmann, ESPN Insider: How can the answer be anything but LeBron? We're again witnessing one of the best (if not the best) players of all time delivering a historic playoff performance by averaging a blistering 34/9/9 -- a feat never before accomplished by a player who logged more than 10 playoff games. Even better that, he's going up against Tatum, one of the best and most clutch rookies in recent history.
Kevin Pelton, ESPN Insider: What happens in close games. Boston is 5-1 in the playoffs in games decided by six points or fewer, while Cleveland is 6-1. What happens when LeBron's heroics go up against the Celtics' late-game execution? The answer could decide the series.
2. What is Boston's best chance to slow down LeBron?
Pelton: Throwing a variety of defenders at him. Brown will probably get the defensive assignment, but Tatum has the size/strength combo needed to match up with LeBron, Marcus Smart defends far bigger than his size and Semi Ojeleye might be the Celtics' best matchup on paper. Rotating defenders will make it more difficult for James to get comfortable against any individual.
Arnovitz: Crisco on the parquet.
Windhorst: The Celtics should play the standard defense against him: Alternate defenders, change up pick-and-roll looks, set your defense to bring help when he goes right (that's when he tends to drive), hack him as much as you can get away with because officials don't call many of them (howl all you want, it's true) and give enough space to try to make him settle for the 3-pointer (especially in isolation situations). That's the book: Follow it and hope for the best.
Engelmann: Boston can never help off of Kyle Korver, who is shooting 46 percent on 3s in these playoffs. And even though it would be nice to have Al Horford as a safety for when LeBron drives, he has had tremendous success slowing down Kevin Love in the regular season, so I'd want that to be Horford's primary focus. I'd help off of everyone else, though, and try to draw as many offensive fouls on LeBron as possible while also giving him a good amount of space. He's bigger and faster than anyone Boston can throw at him, and he has made only 29 percent of his 3s in these playoffs.
Snellings: The Celtics' goal shouldn't be to slow down LeBron, it should be to contain everyone else. We've seen in the past -- such as in the 2009 Cavaliers-Magic series -- that LeBron can put up video-game numbers while his team still loses. The Celtics have a slew of tall, athletic wings whom they can either put on LeBron or switch onto him. Horford is one of the most mobile bigs in the league, so he also can make it difficult for LeBron to get to the rim. But ultimately, the Celtics will be best served by making sure that Love, JR Smith and Korver have another cold series.
3. For this series, which team has the better supporting cast (around LeBron and Horford)?
Arnovitz: A few weeks ago, this was an easy question in the direction of Boston, with the Cavs looking like the Donyell Marshall All-Stars circa 2007. The Celtics have long, athletic wings who can shoot the ball from distance in Brown and Tatum, a dynamic point guard in Rozier -- who has grown into his own as a playmaker and has quickly become a proficient shooter from deep -- and a gritty, do-the-small-things guard in Smart. But the Cavs' reserves have settled into their roles. Korver and Smith are combining for five 3-pointers per game at better than 40 percent, while Love has found ways to be effective and has held his own defensively. It's a push.
Snellings: The Celtics, because their team responsibilities are much more distributed. Horford, Rozier, Tatum and Brown all have major roles that include creation on offense and decision-making on defense. The Cavaliers have a much more concentrated responsibility structure, where only Love outside is counted on for creation beyond LeBron. The rest of the Cavs are role players. Their roles are important, but in a vacuum, the Celtics would be considered better because they aren't really a supporting cast -- they're the actual front line.
Pelton: Probably Boston, by virtue of depth. But the difference in terms of star talent is far greater than the gap in supporting casts.
Windhorst: How'd you pick Horford? Why not Tatum or Rozier? That's the point, isn't it? The Cavs are like a monarchy and the Celtics are like a republic. Boston's star is its cast; Cleveland's star is its team. These teams get it done in different ways. Typically the biggest stars win, but not always -- that's why we play.
Engelmann: If we include coaches, then it's clearly Boston: While Tyronn Lue had the Cavs record one of the worst regular-season point differentials of any LeBron-led team, Brad Stevens guided the Celtics to the No. 2 seed despite two of their best players being out with injuries. From a player perspective, I'd also give a slight edge to Boston. Some Cavs players came alive in the Toronto series, but no one besides LeBron averaged more than 12 points per game against Indiana -- and they'll be going up against an even better defense this time. Meanwhile, Boston's players have made a habit out of stepping up big when needed.
4. If the Celtics pull the upset, how do they do it?
Snellings: The Celtics would need to attack the Cavs from multiple angles. Horford needs to dominate the interior, punishing Love when he's playing center and thus forcing the Cavs to play a non-shooting big man at all times. Rozier needs to play in every game like he does at home. The Cavs have been playing more wings with LeBron playing the point, and Rozier needs to make that into a mismatch that doesn't work. And Tatum, Brown and Marcus Morris need to be aggressive at all times, especially when defended by Korver or Smith instead of LeBron.
Arnovitz: By displaying the kind of defensive discipline they demonstrated during their best stretches of the Philadelphia series, with heady coverages -- smart switches, resistance in the post and barricades around the paint to ward off penetration. Ojeleye and the other young wings aren't going to stop James, but if they can handle their duties one-on-one, the series will look a lot more like the Indiana series for the Cavs than the beatdown of Toronto.
Pelton: The Cavaliers struggled to make 3s, as they did in the opening round against Indiana and the Philadelphia 76ers did against Boston in the conference semifinals. The Celtics need to get enough scoring punch from Rozier and Brown to be efficient offensively, and then lock down Cleveland on defense.
Engelmann: Boston will have played more disciplined basketball than the Raptors, which included not helping off sharpshooters and having smarter shot selection. While the Celtics' league-leading defense lets LeBron get his, it limits the effectiveness of James' supporting cast, most importantly shutting down Love thanks to air-tight defense by Horford.
Windhorst: Execute a game plan that limits Love. When Love isn't active and involved offensively, the Cavs' margin for error collapses. Stevens is probably scheming on that topic as we write this.
5. Who wins the series, and in how many games?
Engelmann: Cleveland in six. Granted, Boston has found ways to overcome adversity all season. But there's a reason LeBron has made seven consecutive Finals. And even though he's 33 years old now, he doesn't exactly appear to be slowing down. The added rest also favors Cleveland's significantly older roster.
Windhorst: Don't do predictions. I will say this, though: The Celtics really need to take advantage of home court and get up 2-0. They haven't been good on the road in the postseason.
Snellings: I have the Cavaliers in six. I've picked against the Celtics in three straight rounds, and in the first two they proved me wrong with excellent coaching and outstanding play from young, relatively inexperienced players. I believe them to be for real. But LeBron has that X factor, that experience, and his ability to lead multipronged attacks at such a high, sustained level should strain even Stevens' coaching and the young Celtics talent. Ultimately, the Cavs should steal one in Boston and close things out on their home court in Game 6.
Arnovitz: Cleveland in six. Every two weeks, we examine the matchup, point to the deficiencies in the Cavs' defense and the lack of a structured system offensively. They look prime for being taken down against teams that far outperformed them in the regular season. I'm done betting against James, even as we should expect maximum effort and intelligence from a Celtics team without conventional star power.
Pelton: Cavs in six. By virtue of home-court advantage and their strong performance against the Sixers, the Celtics can't and shouldn't be ruled out. Still, Cleveland has LeBron, the kind of trump card Philadelphia lacked. If the Cavaliers perform anything like they did versus Toronto, they're headed back to the NBA Finals for a fourth year in a row.