The 76ers opened their two-game preseason schedule with Tuesday’s 108-99 win over the Boston Celtics at the Wells Fargo Center.

Here are observations of coach Doc Rivers’ first game, coaching against one of the former teams that he guided.

Looking at conditioning

All during training camp, Rivers said the No. 1 concern was his players’ conditioning. For the first game, the Sixers looked to be in pretty good shape.

They were active on defense, creating turnovers, and looked effective on the fast break.

In the first quarter, they had 10 assists on 13 made field goals, and many came in transition. The Sixers often had numerical advantages because they were running the court well.

Joel Embiid even benefited from running the break, one time being fed by Ben Simmons and finishing for the layup.

In the second quarter, Simmons posted up, Embiid cut to the basket and Simmons hit him. Embiid was fouled, his reward for hustling to the basket.

Embiid’s conditioning is the main key to the team operating efficiently.

And when he is in shape, he is strong, especially around the basket, where he is the top post-up player in the NBA. This play is a prime example.

» READ MORE: Joel Embiid dominates amid solid spacing as Sixers beat Celtics, 108-99, in preseason opener

The players will have to work their way in getting up to shape to play 30-36 minutes, but for an opening night, the conditioning seemed good.

Green Stuff

Danny Green is supposed to be a glue player, who can do a little bit of everything, including win. His three NBA titles with three NBA teams give him plenty of credibility.

In this game, he defended well, deflected balls, and showed good court presence.

While he might not be the offensive threat that he was earlier in his career, the 33-year-old Green is still a strong catch-and-shoot player, as shown below.

Green also showed an unselfishness, and there was good ball movement with him in the lineup.

Shake as a sixth man

Doc Rivers has had success with high-scoring guards serving as sixth man. As coach of the Los Angeles Clippers, he had Jamal Crawford and Lou Williams each win Sixth Man of the Year twice.

During the preseason, Rivers suggested that Shake Milton could fill that role for the Sixers.

Milton, a starter at the end of last season, appears as if he will come off the bench, and that is no demotion.

Against Boston, Milton was in control, beating players off the dribble, getting to the basket at will.

He still has a tendency to dribble too much, but in this instance it paid off in a feed to Dwight Howard.

» READ MORE: The Sixers are back in the Wells Fargo Center. Where they go from here is anybody’s guess. | David Murphy

As a sixth man, he will be playing against more second-team players, which will give him greater opportunities. He should also see his share of time with the starters.

He seems to play better off the ball, and in the third quarter with Simmons playing point guard, he fed an open Milton, who drilled a three. That is something that should be seen a lot this season.

Whether paired with the starters or reserves, Milton should have plenty of scoring opportunities.

Rivers has also challenged Milton to be better on the defensive end, and in the third quarter, he took a charge against Jaylen Brown in an impressive play.

And finally

Sometimes it is a little dangerous drawing conclusions from the initial preseason game, but before it reached halftime, this Inquirer columnist was already voicing a strong opinion.

It’s a long season and a little levity during the first preseason game was a welcome addition.

» READ MORE: Rockets reportedly want Ben Simmons, 3 first-rounders for James Harden; Doc Rivers willing to take COVID-19 vaccine