NBA opening week: What our experts are watching most closely

New-look Celtics ready for a fresh start (2:07)

Jackie MacMullan breaks down how the Celtics have moved forward after a season of dysfunction and brought in Kemba Walker to strengthen the team's roster. (2:07)

The NBA is officially back.

After Tuesday night's debut featuring the two L.A. squads, the defending champs and the revamped New Orleans Pelicans, it's time for the rest of the league to get things started.

An offseason full of unpredictable player movement means we're probably in store for one of the tightest NBA races in years. To get ready for all the action, ESPN's NBA experts highlight the one question they're looking to see get answered during the first week of games -- including Wednesday night's doubleheader on ESPN/WatchESPN featuring Celtics-76ers (7:30 p.m. ET) and Nuggets-Blazers (10 p.m. ET).

Are the Celtics for real?

Tim Bontemps: It will take only a week for us to get a real first impression of the new-look Boston Celtics. They face the other three teams that advanced in the Eastern Conference playoffs last season -- the Philadelphia 76ers, Toronto Raptors and Milwaukee Bucks -- within the first eight days of the regular season.

It will be an instant test of Boston's new group, particularly its rotation of centers hoping to try to fill the very large shoes of departed All-Star Al Horford. That was a work in progress during the preseason and probably will remain one for quite some time. Just how much work Boston has to do on both ends should be clear after one of the league's most difficult opening slates.

Is the Warriors' defense good enough?

Chris Herring: For the first time in five years, the Golden State Warriors won't begin the season as favorites in the West. Many wonder how they'll look on offense without Kevin Durant or Klay Thompson, whose timetable for a return from his ACL tear is in question. But the defense -- with D'Angelo Russell and without Andre Iguodala, Durant or Klay -- could take a considerable step back, too.

Golden State's ability to get stops will be tested out of the gate Thursday as the Warriors host Kawhi Leonard and the Clippers, who have arguably replaced the Dubs as the league's top title contender.

How -- and when -- will coaches use their brand-new challenges?

Andrew Lopez: The NBA's one-year experiment with coaches' challenges got off to a rocky start Tuesday night, with Nick Nurse and Alvin Gentry going a collective 0-for-2. Nurse dropped his in the first quarter while Gentry used his in the third.

What will be interesting in the first week is how other coaches use theirs. Will they use it out of pure frustration on a timeout that is already coming? Will they save it for a key play in the fourth quarter? Or will they forget about it altogether and hope it goes away?

Will a Russ transformation last?

Royce Young: Russell Westbrook is almost assuredly going to open his Houston Rockets tenure trying to play a different way. He's going to defer to James Harden. He's going to spot-up and cut and screen. He's going to play the analytical game. He's going to try to fit in. This isn't atypical for Westbrook in changing situations; he has done it before with new teammates.

The question is: What's the over/under on it lasting? One week? One month? One season? The chemistry and motivation to make it work is there for Westbrook and Harden, but can it mechanically? Is it destined to malfunction, or can two of the most ball-dominant stat-stuffers ever actually play together?

How does Kyrie fit in with the Nets?

Baxter Holmes: Chemistry can be forged over a season, but first impressions -- as with anything in life -- can be lasting. By any measure, Kyrie Irving wore his teammates thin in Boston last season, creating vast sums of friction with his postgame comments.

Irving has a new roster in Brooklyn and how he meshes with those players early could be key in helping establish himself as a leader for the franchise down the road. There's no doubt the pressure will be on Irving right away given how poorly things worked out last season.

Can the Bucks rely on their bench?

Malika Andrews: Save for swapping Malcolm Brogdon for Wesley Matthews, the Bucks' starting lineup looks largely the same. It's the team's new supporting cast that I am excited to see in the opening week. In the playoffs last season, it was Milwaukee's bench -- primarily Pat Connaughton and George Hill -- that helped propel the Bucks to the Eastern Conference finals. Now, they've added Kyle Korver, another sharpshooter who boosts the Bucks' space-and-pace system. Robin Lopez will add an imposing defensive presence off the bench.

Milwaukee's depth is its secret sauce. How will this season's sauce compare to the flavor of last season?

Does Miami look like an East contender?

Dave McMenamin: I'm really curious about the Miami Heat. During the offseason when I had to get my basketball fix from podcasts, I heard smart people I respect like Zach Lowe and Doris Burke tout Miami as a sleeper to make some noise in the East.

They get the Bucks this weekend, which is an early eye test. Can the Jimmy Butler-infused version of the Heat -- with tough, switchable guys around him in Justise Winslow, Bam Adebayo and Derrick Jones Jr., sprinkled in with some shooting from Goran Dragic and rookie darling Tyler Herro -- keep up with a contender?

Can the Clippers actually score?

Andrew Han: Preseason is by no means a projection, but the Clippers struggled to generate efficient offense as a group. Granted, Paul George is sidelined for the first few weeks as he recovers from shoulder surgery, but his return would only add another solo shot maker.

When Kawhi Leonard and Lou Williams are on the court, offense is generated through them. But unless Montrezl Harrell is rim-rolling, it remains to be seen whether the Clippers can make teams pay for loading up against their prodigious scorers.

Will Luka and Porzingis click?

Mike Schmitz: On paper, Kristaps Porzingis and Luka Doncic are one of the most exciting under-25 duos in the NBA. Coach Rick Carlisle can employ a variety of different Doncic-Zinger pick-and-rolls, with either as the ball handler. Even so, I'm curious to see how the 20-year-old Doncic balances getting his own with allowing Porzingis to isolate out of the post the way he did so often in New York.

Both are ultra-confident competitors, and I'm fascinated to follow the on- and off-court chemistry between the international stars. If they click, the Mavs figure to be a League Pass darling and playoff sleeper.

How ugly will things get in Charlotte?

Bobby Marks: There are no closed-door team meetings (yet) and the job security of head coach James Borrego is safe, but circle the Charlotte Hornets' first two home games against Chicago and Minnesota. Things could get ugly if the Hornets drop both contests.

Predicted to finish in the bottom of the Eastern Conference, Charlotte could be 0-10 before we even hit mid-November. After hosting the Bulls and Wolves, the Hornets head out on the road to face both Los Angeles teams, Sacramento and Golden State, then they return home for Indiana, Boston and New Orleans before finally playing at Philadelphia. If the Hornets don't win in the first week of the season, the 2009-10 New Jersey Nets' steak of 18 straight losses to start a season could be in jeopardy.

Do KAT and the Wolves surprise?

André Snellings: Is Minnesota ready for a leap? Two seasons ago, the Timberwolves entered March at No. 3 in the Western Conference, but then they lost nine of 15 games with Jimmy Butler injured, limping into the playoffs. Last season was doomed from the start when Butler forced his way out of town.

But Karl-Anthony Towns played at an MVP level after the Butler trade and he's approaching his peak. When healthy, Robert Covington is a defensive force with two-way ability. Add in some talented perimeter players and defensive strides from Towns and this season's Wolves could be sneakily formidable.

How comfortable is Golden State's new All-Star?

Nick Friedell: I want to see how D'Angelo Russell fits into the Warriors' system. Stephen Curry and his teammates are trying to make sure Russell gets comfortable early.

If Russell can take some of the offensive burden off Curry in the first few weeks, it will help the organization navigate all this time without Klay Thompson.

Who's winning the L.A. sneaker battle?

Nick DePaula: The retooled Clippers and Lakers may be battling on the court for local bragging rights, but the star players on each team have also found themselves in a marketing tug-of-war throughout the region. Nike's massive 18,000 square foot digital billboard engulfed the corner of Figueroa Street near Staples Center this week, featuring taglines over the respective shoulders of Paul George and Anthony Davis: "Everything shines brighter in LA," read George's. It was opposite AD's: "Write your own Hollywood ending."

New Balance launched its own "Kawhi's Funhouse" pop-up over the weekend, selling Leonard's OMN1S sneaker for the first time at retail. And LeBron's legacy with Nike continues with the upcoming launch of his 17th signature model, the longest consecutive series for an active player. Tracking which star has the advantage in this loaded market will be fascinating early on and all season long.