Doc Rivers has less than a week to make some big decisions.

While his starting five is obvious at this point, the 76ers’ first-year coach has to figure out who’s going to be in his full 10-man regular-season rotation for when the team kicks off its season against the Washington Wizards on Wednesday at Wells Fargo Center.

“I have a good sense. I don’t know if I have a clear sense yet,” Rivers said of his reserves. “At least for four, for sure. I can tell you that in my mind.”

Who are the four?

“I will let you know,” said Rivers, followed by laughter. “You will figure it out, I guarantee.”

Guarantee?

“You will eventually when you keep seeing that same group,” he said.

Shake Milton, Furkan Korkmaz, Dwight Howard, and Mike Scott were the first four off the Sixers’ bench in Tuesday’s 108-99 preseason victory over the Boston Celtics. Philly heads to Indiana to face the Pacers Friday night in their second and last preseason game.

It can be assumed that Milton, Howard, and Korkmaz will be in the rotation. We could get a better sense of who that fourth player will be during Friday’s game against the Pacers, if Scott is, once again, one of the first four to leave the bench.

The power forward provides depth in the frontcourt and adds another shooter on the floor. Swingman Matisse Thybulle is one of the team’s best perimeter defenders. He could take up the slack in that area when Danny Green and/or Ben Simmons are out of the game.

And there’s rookie Tyrese Maxey, who showed Tuesday night that he can bring excitement to the rotation.

“He’s gonna push for minutes because he’s a good basketball player,” Rivers said of the combo guard out of Kentucky following Tuesday’s game. “He knows how to play. You can’t speed him up, he’s got a plethora of shots.”

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But if the Sixers do indeed go with a 10-man rotation, someone deserving is going to be left out.

Shooting and defense are important qualities for that 10th spot.

“[It needs to be someone] who can get the team and run the rest the best,” Rivers said. “I mean, there’s a lot of little things. We may need more size. So we will see.”

Overall, the focus heading into the final preseason game is a better showing than Tuesday night.

There were times when the Sixers lost their pace, and it hurt them. And that’s not all.

“With that one game, you could see [when] a couple of mistakes don’t go your way, everybody’s hanging their heads,” Rivers said. “We got to just keep playing. Those are little things.”

The Sixers have to be better in transition defense as well as pick-and-roll defense. The coach thinks the pick-and-roll defense got exposed around eight times. That has to be corrected.

“So we have a lot of work to do is what I see,” Rivers said, “and I want to see us improve in this next game.”