Shams Charania of Yahoo Sports reported the news Wednesday.
Lillard injured his left ankle late in Tuesday's win over the Dallas Mavericks.
"I think I have a pretty high pain tolerance, but I'm going to be smart about it," Lillard said afterward, per Jason Quick of NBC Sports Northwest. "It's the end of the season, we are going into the playoffs, so I have to be smart that one thing doesn't turn into another."
The Blazers are nearly locked into the third seed in the West, so there isn't much incentive for Lillard to play while hurt. They're one of only three Western Conference teams to have clinched a playoff spot heading into Wednesday, so getting Lillard healthy for the postseason is far more important than seeding.
"It's sore, man," Lillard said of his ankle Tuesday night, per Quick. "I was just in a vulnerable position...it's painful. I was able to finish the game, but it was worse when the game was over. (I'm) dealing with a lot more pain and swelling."
Shabazz Napier likely will get the start against Houston with Lillard out of the lineup. The Blazers have gone 5-3 without Lillard this season, though they'll be a significant underdog against the top-seeded Rockets.