When the typically gruff Knicks coach Tom Thibodeau took the podium on Wednesday night, he did something out of character. He opened his news conference with a smile.

He had just sat — or rather, stood — through a double-overtime thriller to start the season against the Boston Celtics, a game that featured 11 lead changes and 10 ties. It was the first time that a Knicks home opener went into double overtime.

“The good thing is, at the end of the day, we got the win,” Thibodeau said of the Knicks’ pulling out the 138-134 victory.

It was only a regular-season game, but it felt like the basketball equivalent of the Iliad. There were star performances on both sides, like Jaylen Brown’s career-high 46 points for the Celtics after his recent bout with Covid-19, and Julius Randle’s 35 points, picking up right where he left off from carrying the Knicks last season. Even before halftime of opening night, Randle’s performance had the Garden crowd chanting “M-V-P!” again.

There was peak basketball, like Robert Williams III, the Celtics center, scoring 16 points on only five shots, and his Knicks counterpart, Mitchell Robinson, doing virtually the same thing on the other end.

And there was absolutely atrocious basketball, like the Knicks’ making a defensive miscue to free Celtics guard Marcus Smart for an improbable (and uncontested) 3-pointer that tied the score at the regulation buzzer and sent the game to overtime.

Not to be outdone, the Celtics missed a wide open dunk and layup that could have sealed the game in the second overtime.

Both teams were without key players: the Celtics without Josh Richardson and Al Horford, and the Knicks without Taj Gibson and Nerlens Noel. And while there aren’t many conclusions that can be drawn from only one game, especially the first one, Wednesday night made clear that there are some options on the new-look Knicks that they didn’t have last season.

Last year, the Knicks had difficulty taking pressure off Randle, particularly with shooting the ball from the perimeter to create space for him late in games. The signing of Evan Fournier, a 28-year-old in his 10th N.B.A. season, appears to have given the Knicks a human release valve.

Fournier made six 3-pointers on Wednesday night, including one in the final minute of the second overtime to give the Knicks the lead for good. He finished with 32 points, much to the relief of a grateful Randle. He was another valuable option in crunchtime that had to be accounted for.

“He came up super clutch in those overtimes,” Randle said. “Hit some big shots. So I just wanted to keep finding him. But Evan is great, man. He’s really smart. We talked after the game. There’s things that we feel like we can do better and work on. He has an extremely high IQ.”

The Knicks also saw good signs from Obi Toppin, who came off the bench with 14 points in 28 minutes, the most he had played in a game so far in his career. The Knicks were 4 points better with Toppin on the floor, and his strong play allowed the team to play small and move Randle to the center position. That gave the Knicks a lineup that was more nimble.

“Obi is really learning how to become an N.B.A. player,” Fournier said. “From what I saw from him last year, he’s really getting better and better. He understands how to make himself efficient.”

It was how Toppin made his presence felt that is likely to encourage Thibodeau to make him a permanent part of the rotation. He routinely put the Celtics’ defense on its heels through sheer energy and running the floor at full sprint to create opportunities for himself. Toppin, now in his second season, missed all three of his 3-pointers and is not yet a reliable shooter, but on Wednesday he made enough smart cuts to compensate for it.

“Juice tells me when I’m on the court with him, if I see that he has the rebound, take off,” Toppin said, referring to Randle. “That’s what I do best. I run the floor. Every chance I get, I’m getting out in the open floor.”

That will be useful for the Knicks, who were middle of the road in pace last year. Toppin’s efforts were rewarded.

“Man, hearing your name chanted in the Garden is amazing,” Toppin said. “It’s an unbelievable experience I can’t even explain. It’s just something you’ve got to live through.”

This was the kind of regular-season atmosphere that hadn’t been possible during the pandemic, even if it was only one game starting a long slog of a season.

But in a competitive Eastern Conference against a division rival, one game could be the difference between having home court advantage and not, as the Knicks themselves found out last year to their benefit. With high aspirations, every victory matters.

“I don’t think we escaped,” Randle said. “We made some mental mistakes, errors or whatever. At the end of the day, we found a way to win a game.”