McGrady has missed the Rockets' past five games, all losses, with a recurring back injury. Houston is 0-8 without its best player this season.
The All-Star completed a full practice Monday but had to sit out portions of Tuesday's morning walkthrough when his back tightened.
"It's tough for me to run up and down the court and then when we stop and go through [the game plan] -- just standing around, that's not good for me," McGrady said. "It just depends on how I feel when I come to the arena tonight."
McGrady, though, expressed a belief that, if he chooses to play against the Hawks, the constant movement in a game situation would keep him sufficiently loose. The Rockets also have three off days after hosting Atlanta before Saturday's home date with Memphis.
"I definitely don't want to come back and then have to sit myself down and set the team back again," McGrady said. "That's why I'm taking my time on getting back and just being cautious about it."