On Monday night, the 5-1 Boston Celtics will visit the 6-1 Houston Rockets (8:30 p.m. ET) in a battle of two of the NBA's best teams in the early going.

The game would be a test no matter what given how good the Rockets are, but it is even more of a test for two specific reasons:

1) It's night two of a back-to-back for the Celtics

2) Paul George isn't playing, as he's out with rest

Let's address point one first:

The Celtics beat the Orlando Magic 108-97 on Sunday afternoon to move to 5-1. Jayson Tatum led the way with 32 points, but he got help from several others as well. Playing two nights in a row is never easy, especially when both games are on the road and involve fairly significant travel.

This game will test the Celtics' health, mental resolve, conditioning and focus. 

On the positive side, they get Mitchell Robinson back in this one. He was out on Sunday for rest himself.

After playing each of the first six games, including the first back-to-back of the year, George gets his first rest in this one. It's understandable considering that George's health has been a major issue for years. He's played 60 games or less in six of the last seven seasons and the Celtics evidently want to keep him healthy as much as they can, and hopefully into a deep playoff run.

But it's fair to acknowledge this: The Celtics have been excellent with him on the floor, and he's played well both offensively and defensively. I've said that I think the Celtics can be a really good team with him, but it's also my fear that he won't be on the floor often enough to help them hit their ceiling.

No, he's not hurt right now, but we're going to get a look at what the team looks like without him on the floor. I fear that the Celtics are going to look very different without him, and that's going to give me great pause for how the season can go if he's out of the lineup often.

And history says he will be. And again, that's my biggest fear.

In order to quell that fear, we'll need to others step up in his absence, including Derrick White, Payton Pritchard, Baylor Scheierman and Hugo Gonzalez.