Playing without Jaylen Brown and Marcus Morris, the Celtics improve to 22-4 with a 97-90 win over the Dallas Mavericks Wednesday night.

BOSTON – The usual reasons can be used to explain yet another Celtics’ victory, their 22nd in 26 games this season.

There was the clutch fourth-quarter play of Kyrie Irving, the versatility of Al Horford and the steadiness of rookie Jayson Tatum.

But the Celtics needed more than that to get past the Dallas Mavericks, 97-90, Wednesday night at the TD Garden.

With two key parts of the rotation – Jaylen Brown (eye) and Marcus Morris (sore knee) – missing, the Celtics had to get some help from others who aren’t usually relied on.

Down to 11 players, the Celtics turned to Shane Larkin, Guerschon Yabusele, Abdel Nader, Semi Ojeleye and Daniel Theis, and they all did a little something to contribute to a fourth straight Celtics’ victory.

“We mentioned it at shootaround that everybody just has to be ready,’’ said Terry Rozier, who had 12 points and nine rebounds off the bench, “especially when you can call to anyone on your bench and they are ready.

“We had the next-man-up mentality. We just are covering for one another and we’re a team and we are pros for a reason. We put in all this hard work and you’ve got to be ready.’’

Irving did his thing in crunch time yet again, scoring nine of his 23 points in the fourth quarter as he took over with the game even at 85, scoring seven of the Celtics’ next 10 points.

“Just winning time,’’ said Irving after his team rallied from 12 points down for the win. “It’s always fun. It’s fun for me. You have to go into your bag of tricks.’’

Horford scored 17 points to go with eight rebounds and eight more assists and Tatum chipped in with 17 points and 10 rebounds.

Larkin, who has been unable to play recently after hurting his back in a fall at Miami, scored 11 points with three 3-pointers.

Theis grabbed 11 rebounds to go with seven points in 18 minutes and Ojeleye found himself matched up with future Hall of Famer Dirk Nowitzki.

Nader and Yabusele, who have played 12 and eight games, respectively, both hit 3-pointers in the second quarter when the bench had a productive stint with Yabusele getting three assists and two rebounds in seven minutes.

“It’s their first year in the league,’’ said Larkin, “and I just tell them, listen, you have no idea when that opportunity’s going to come.

“When you get that chance, you’ve got to go out there and not score 30 points, not have 10 rebounds. Make impact plays and make sure when you leave the court, things are going better than when you got on the court. They did a great job tonight.’’

Coach Brad Stevens, whose team went 4-1 on the longest homestand of the season, knew he was going to have to go deep into the bench without Brown and Morris.

All 11 players had seen action just over two minutes into the second quarter. At one point, the lineup included three players who were in Europe last season (Yabusele, Theis and Larkin), Nader (who was with the Maine Red Claws) and Rozier.

“They haven’t gotten a lot of opportunities here yet,’’ said Stevens of Yabusele and Nader, “but inevitably they will because in the NBA you can have days like today where all of a sudden you’re down to 11 guys and the next man’s got to be ready.’’

The little-used youngsters helped keep the Celtics afloat and Irving closed it out to keep the Celtics rolling even without two key players.

“(We’re) very confident,’’ said Horford, whose team allowed just 33 second-half points. “ It all starts with Kyrie for us, everybody knows that. He came in and made some big plays, some big shots.’’