"He has a lung contusion," Kubiak said, according to the Texans' Web site. "(Team doctors) feel good about it. They feel like he's going to be fine. I think, obviously, he's going to be day to day as we go into this week. They'll do some tests on him each day as we go through this week, but I think we're fortunate here and hopefully he'll be ready to go against Buffalo. But he'll be day to day."
Johnson, a three-time Pro Bowler who has 38 receptions for an NFL-leading 634 yards and four touchdowns, was injured Sunday when he took a hit in the lower back during the second quarter of the Texans' 24-21 victory over the San Francisco 49ers. Johnson remained in the game, but he began coughing up blood after landing on the ball following a 44-yard catch early in the fourth quarter.
"Well, that's him," Kubiak said of Johnson, according to the Texans' Web site. "He wants to do whatever he can do to help this team win, and yesterday was a struggle getting him the ball. He had two plays that were both big plays. But Andre will give you everything he's got, and you all know that. He knows this team needed a couple more plays to win, and he was willing to go make them."
Johnson returned for one play after his 44-yard catch and wanted to stay on the field, but the Texans' medical staff escorted him off during the team's final drive.
The Associated Press contributed to this report.