BOSTON — Kevin Durant had no room. He admitted as much. Whenever he had the ball against the Celtics on Wednesday night, and even when he did not, defenders were crowding his space, shadowing him, draping themselves all over him like Saran wrap. They were on the perimeter, and in the paint, and at the elbow. How was it possible that only five of them were on the court at once?

“They’re mucking up actions when I run off stuff,” said Durant, who singled out the Celtics’ Al Horford for “leaving his man to come over and hit me sometimes.” Durant went on: “Just two or three guys hitting me wherever I go. And that’s just the nature of the beast in the playoffs.”

It was nearing 11 p.m. as Durant offered up his post-mortem of the Nets’ 114-107 loss to the Celtics in Game 2 of their first-round playoff series, and he did not necessarily seem concerned. In fact, his analysis came off as dispassionate: Here were the facts, and it was his job to remedy the issues as the Nets seek to rebound from their two-games-to-none deficit in the best-of-seven series. It heads to Brooklyn for Game 3 on Saturday night.

“It’s on me to just finish it and figure it out,” he said. “I’m not expecting my teammates or the defense to give me anything. I just got to go out there and play.”

Durant is having an atypical series. In the Nets’ loss in Game 1 on Sunday, he shot 9 of 24 from the field and committed six turnovers. In Game 2, he shot 4 of 17 from the field and committed six turnovers. The Celtics, with their length and toughness, produced the N.B.A.’s top-ranked defense during the regular season, and now they are putting the clamps on the best all-around scorer on the planet. It is no fluke.

“When you’re a great scorer, or you’re a consistent scorer, you’re used to seeing open space, and you’re usually shaking guys with one or two moves,” said the Nets’ Kyrie Irving, who had his own problems, scoring 10 points while shooting 4 of 13 from the field. “But with this defense, those two or three moves, guys are staying on your hip.”

You may have heard this already, but the Nets have had a turbulent season. At one point, James Harden played for them, until they traded him away for Ben Simmons. Irving was not allowed to play for the Nets, and then he was — but only on the road, up until about a month ago. And stay tuned: Simmons may actually make his debut for the team in this series. The bottom line is that the Nets have never had much cohesion.

It would be a mistake, of course, to count them out. Durant and Irving are capable of doing extraordinary things all by themselves. But the Celtics are determined — they trailed on Wednesday by as many as 17 points before mounting a comeback — and they have two stars of their own, Jayson Tatum and Jaylen Brown, who have finally unlocked their own brand of chemistry. Irving sounded like their publicist.

“I’m not surprised at all,” Irving said. “I just think the timing is right. Their window is now for these young guys that are on this team that have matured. They’ve been through series together, they’ve been through seasons together, and they’ve been through battles together.”

On Wednesday, the Celtics were ready for a fight. A couple of hours before the game, Marcus Smart, the team’s starting point guard, made a statement when he showed up to the arena wearing a bedazzled boxing robe with the acronym “D.P.O.Y.” splashed across the back. In a pregame ceremony, he formally accepted the N.B.A.’s Defensive Player of the Year Award from a cast of luminaries that included Gary Payton, who was the last guard to claim the award, for the 1995-96 season.

Still, pretty much everyone in the building expected Durant to bounce back from his struggles in Game 1, and for good reason. Last season, he averaged 41.8 points in the four games that followed playoff losses for the Nets. Ime Udoka, the coach of the Celtics, was acutely aware of that statistic. He cited it before Wednesday’s game.

“Just understanding what he’s going to come out and try to do,” Udoka said. “We all know that.”

Udoka, especially. Last season, he was one of Nets Coach Steve Nash’s assistants. Udoka has institutional knowledge, and he has been putting it to use.

“They switch everything,” Durant said. “They’re basically playing a zone so it’s easier for every player. They don’t have to chase over screens, don’t have to fight through stuff. Just use your length, sit in the lane and help.”

At his postgame news conference, Durant kept glancing at the box score as if it were a riddle he needed to solve. He made a few observations. He observed, for example, that the Celtics had seven players score at least 10 points, which was indicative of their balance. He also observed that “they made a few more shots than us.”

Solutions were not forthcoming — not yet. On the one hand, the Celtics merely maintained their home-court advantage in the series. On the other hand, the Nets are in dire straits: They need to win four out of the next five games, potentially. The math is unforgiving.

“To be honest with you, we don’t really have time to be disappointed,” Irving said.

Perhaps Durant’s minutes are beginning to take a toll. In the final weeks of the regular season, the Nets needed to scramble to assure themselves of a spot in the postseason, and Durant shouldered a heavy load: 42 minutes against the Charlotte Hornets, 45 minutes against the Milwaukee Bucks, 42 minutes against the Atlanta Hawks. He also supplied more than 40 minutes in the final game of the regular season, a 5-of-17 shooting performance against the Indiana Pacers. It was, in its own way, a sign of things to come against the Celtics.

Ahead of Saturday’s game, Durant said he would study film. He expressed faith in his teammates.

“The name of our game is just to play extremely hard,” he said.

The problem? That’s the Celtics’ game, too.