The Celtics were playing before a crowd of 18,624 at the Garden last night, seeking to improve their immediate future by retaining the No. 1 seed in the East with less than two weeks remaining in the regular season.

Meanwhile, 638 miles away, the Dancing Bear was getting his paws wet in Greensboro, N.C., as 2,284 looked on at The Fieldhouse. Guerschon Yabusele, one of three C’s first-round picks last June, was making his debut with D-League Maine after a season in China — and doing quite well.

The numbers aren’t important. But the numbers, particularly under the circumstances, were impressive. Playing for the first time since injuring his left ankle in his China finale four weeks prior, he came off the bench for the Red Claws and recorded 17 points and nine rebounds in 25 minutes. In the 122-105 Maine loss to the Swarm, he still managed to be a plus-2.

He’s a slice of Shamrock future still several months from potential impact, but assistant general manager Mike Zarren was parked in a room off the backstage hallway at the Garden watching Yabusele on a TV hooked to his laptop. He left when the Celts and Magic tipped off, but he was back at halftime, and he was watching the D-League replay even more closely last night.

“I’ve got to watch the rest of it, but it looks like he’s moving well, which is good,” said Zarren. “He doesn’t look out of place on the court, and he hasn’t played in a month — and not with this level of guys since summer.

“Even just getting used to the NBA style of officiating before he has to play in summer league and for us is great. He’s getting to know some of our plays. The Claws run a lot of our plays. And any on-court experience for a kid his age is great.”

Yabusele, the No. 16 overall pick, hit half his eight shots and nine of his 10 free throws.

“We know he can shoot,” Zarren said. “I’m not worried about whether or not he makes shots tonight.”

It’s been an international whirlwind for Yabusele, moving from his native France to China and to Boston to rehab his ankle. Then to Maine this week after getting his U.S. work visa.

He entered some four minutes into the game with the Claws down by four. He looked a little tentative on the dance floor early, but when the first rebound was available in his vicinity, he was very much a bear, hauling in the offensive board. (Five of the nine caroms he took down were on that end.)

A half-minute later, Yabusele found himself switched onto Damien Wilkins out high.

“This is not the matchup you want to see,” said Zarren.

A split-second later, his concern was given testimony. Wilkins faked Yabusele off his feet and drew the foul. The contrast was striking. The 21-year-old Dancing Bear was playing his first professional game — his first minutes — in the United States (he wasn’t under contract during summer league), while Wilkins is 37 with nine years of NBA experience. He’s trying to make his way back to the big league after three seasons overseas and in the minors.

Yabusele had a size advantage, but it was actually more of a disadvantage. At 6-foot-7, he’s an inch taller than Wilkins, son of Gerald, but, according to the program, he’s 35 pounds heavier. That made it no surprise at all when, owing to rust and quickness matters, he sent the veteran to the line twice more in the half.

“It’s good that he’s learning it here,” said Zarren in a glass half-full statement that really wasn’t a reach.

A 3-pointer that went long, another jumper that was short — all to be expected. And help defense was an issue early on, a problem that is essentially circuit-wide amid changing D-League rosters and among players generally more interested in showing well individually.

Still in his first minutes, Yabusele bulled his way in for another offensive rebound and was fouled as he tried to convert. He smoothly hit both free throws. A missed floater and some good box-out instincts later (the latter of which will certainly get Brad Stevens’ attention when he sees the video), the rookie took a seat with two points, three rebounds and two fouls.

He hit another two foul shots in the second quarter as strength coach Bryan Doo, who’s been working on the Bear’s body transformation since last July, stopped by the room and said, “Bet he makes them both.”

The only miss was by Doo, who had gone back to the Garden floor when the Bear got loose.

Near the mid-point of the frame, Yabusele decided to go for a power drive and an even more powerful jam. By the end of the move, the Swarm had wisely dispersed. Do they have posters in the D-League? The Greensboro guys seemed to act that way.

As much as he had to be getting winded later on, Yabusele seemed more in step. His fourth offensive rebound turned into another bucket, and he scored on a drive on the next Maine possession. Later he stuck what appeared to be a 3-pointer, but it was ruled a 2 at the time and remained that way when replays were inconclusive.

Zarren had left to watch the varsity out on the Garden floor when Yabusele began exhibiting a rather sharp learning curve. He was much better able to hold his ground and control space when he was reunited with Wilkins in the fourth quarter on another switch.

It wasn’t exactly LeBron’s career-opener before a national television audience, but for a guy in a new country who was drafted two away from the lottery, it was more than bear-ly encouraging.