On Tuesday night at Barclays Center, Stephen Curry will take the floor for the Golden State Warriors and Steve Kerr will coach the team in its first meaningful game in more than nine months. The considerable wait to get back to work is where the oddities only begin for Kerr.

As he returns from the longest hiatus he has known in an N.B.A. career that began when he was a rookie in 1988-89, Kerr must confront two familiar faces leading the Nets. He will be coaching against Kevin Durant, the co-pillar of two Warriors championship teams alongside Curry, and against a good friend, Steve Nash, who will be making his official debut as the Nets’ (and Durant’s) coach.

It is a lot to track in terms of story lines and, at the same time, it is only half the story on opening night of the N.B.A.’s 75th season. To lead off a schedule that was moved up to begin just before Christmas, after strong urging from the league’s television partners in their quest for maximum profit, Warriors vs. Nets comes amid a pandemic that is wreaking its worst havoc yet across the United States.

“We are in the same boat as a lot of people out there,” Kerr said. “Everything is strange for everybody. We’re lucky to be working, and we recognize that. So we are embracing our circumstances rather than lamenting them.”

There figures to be enough worry to go around, from various corners of the league, even if Kerr manages to stifle his concerns. The N.B.A. is starting anew after its shortest off-season ever and will do so in the coronavirus-ravaged real world, just 72 days removed from the Los Angeles Lakers’ emerging as champions from the league’s bubble at Walt Disney World near Orlando, Fla.

There will be no fans allowed inside Barclays to witness the various reunions for Kerr, Durant, Curry and Nash, but there will also be no bubble to protect the participants. The N.B.A. is counting on daily testing of players, coaches and team staff members, vigilant mask-wearing and social distancing, and an expanded book of health and safety guidelines to get through the winter — even as public health experts project January to be the most devastating month yet in the country’s battle against the virus.

All 30 teams will also have a league-assigned “protocol officer” with them on the road and on team planes, trying to ensure adherence to the many restrictions outlined within the league’s nearly 160 pages of rules to govern the season.

Dr. Anthony S. Fauci, the country’s top infectious disease expert, recently predicted that access to a Covid-19 vaccine should be widespread nationally by late spring or early summer, with those who have no underlying conditions likely able to be vaccinated by the end of March or the beginning of April. The months until then, however, could be grim — something the N.B.A. has essentially acknowledged by releasing only the first half of its regular-season schedule, through March 4. The league office wants to maintain calendar flexibility to deal with the sort of coronavirus-related disruptions that have upended other sports, such as the N.F.L. and college football, which have not employed bubbles.

“We know there are going to be challenges and bumps, but so far things are good and we’re optimistic that we have a plan that we can work through those challenges and bumps,” said David Weiss, the N.B.A.’s vice president of player matters.

Mark Cuban, the owner of the Dallas Mavericks, said: “We won’t be able to eliminate cases and outbreaks. But if we can minimize them, then hopefully it can be as close to a normal season as possible.”

There is some optimism to be gleaned from a declining number of positive coronavirus tests among players over the past three weeks. Since the league resumed regular testing just before Thanksgiving, the number of players testing positive has dropped to just one on Wednesday from eight the week before and 48 the week before that. Of course, encouraging as that sounds, leaguewide travel only began Dec. 10 and is poised to increase significantly.

The Warriors, for example, played only two preseason games on the road and bused back and forth to Sacramento on game day for both of them, while spending the day in between at home to minimize exposure to unfamiliar elements. League rules, during the regular season, would have prevented Golden State from leaving Sacramento between games. The Warriors are scheduled to travel to New York on Sunday in advance of Tuesday’s opener against the Nets and have stops in Milwaukee, Chicago and Detroit before returning home nine days later.

The N.B.A. won considerable plaudits for the manner in which it engineered and orchestrated its bubble. The N.F.L., in stark contrast, is mere weeks removed from the fiasco of the Denver Broncos’ playing the New Orleans Saints without a recognized quarterback after a spate of mask-wearing violations. The reality, though, is that N.B.A. teams — playing a high-contact, face-to-face, indoor sport that, with three to four games per week, requires much more travel — will face conditions that their N.F.L. counterparts do not.

“We expected that the numbers would go down during this first phase of testing, as people started following the protocols,” Weiss said. “At the same time, we know that doesn’t mean that we won’t have cases. We know we’re not in the clear, and we can’t get complacent. We have to stay vigilant with the protocols. That’s how we succeed.”

“The most important aspect,” Cuban said, “is that the players and staff that are traveling are treating each game as a self-imposed bubble.”

Seven of the league’s 30 teams have decided, after receiving clearance from local jurisdictions, to allow a reduced number of fans into their buildings as the season begins: Cleveland, Houston, Memphis, New Orleans, Orlando, Utah and the Toronto Raptors, who have temporarily relocated to Tampa, Fla., because the Canadian government refused to allow teams to enter the country without 14-day quarantines.

The eight teams that were not invited to the bubble, Golden State among them, have not played a game that counts for more than 280 days. The Lakers and the Miami Heat, after battling for six games in the N.B.A. finals, were back in training camps less than eight weeks later. There will be rest and recovery inequities for numerous teams over the 72 regular-season games — down from the usual 82. The league compressed the schedule by 10 games to avoid infringing upon next summer’s rescheduled Tokyo Olympics and, most of all, to get on track for a return to its customary October-to-June calendar for the 2021-22 season.

Orlando’s Evan Fournier expressed sympathy for the ultratight turnarounds that his Lakers and Heat peers face, but said: “The rest of the league, we’ve got to play.”

That became a near-universal view once it was made clear to the N.B.A. players’ union that the difference between a pre-Christmas start and opening on Martin Luther King’s Birthday on Jan. 18, as many players had hoped, would lead to a revenue shortfall of at least $500 million.

Things were so different in March, when the N.B.A. was the first major professional sports league to suspend play in response to the coronavirus outbreak and instantly became an exemplar for sports organizations worldwide. Nine months later, with a coronavirus outlook still so dire, other leagues aren’t waiting around to take cues from the N.B.A. Seemingly every organization in sports is trying to sculpt its operations manual to find a workable balance between risk-taking and economic necessity.

The N.B.A. is about to re-enter the fray in earnest — this time trying to learn from what other leagues have done wrong.

“We’re doing fine,” Kerr said. “It’s not the normal set of circumstances by any means, but it isn’t for anybody.”