After some stretching and jogging, Wright tried to test it, only to go back to the sideline a few snaps later.
"My leg was hurting a little bit, so I just got to play it safe," he said. "We've got plenty of days to get better. I didn't want to do something I might've regretted."
Schwartz said defensive tackle Corey Williams, who hurt his left ankle during practice, also has a day-to-day injury.
With Wright and Houston watching from the sideline, Aaron Berry, Nathan Vasher and Brandon McDonald were given chances to practice with the Lions' first-string defense. Detroit plays its second preseason game Friday at Cleveland, where Wright, Williams and McDonald and running back Jerome Harrison all played.
Wright played for the Browns during his first four seasons in the NFL, starting 13 games as a rookie, every game the next two years and 10 last year before having a season-ending injured left knee. He had 11 interceptions, including seven in the 2008 and 2009 seasons.
Wright was beaten badly for touchdowns early last year, and then-rookie Joe Haden eventually got his job. If Wright is bitter about his experience with the Browns, he's trying to keep it to himself.
"It's the second preseason game," Wright said three consecutive times, dodging questions about playing this week in Cleveland.
On a fourth attempt, Wright budged a little.
"I have great memories from Cleveland," Wright said. "They drafted me in '07 -- moved up to draft me."
"The main thing is, you want to enter the regular season healthy," Johnson said. "It's not about going out there and getting it hurt again in the preseason. I want to be able to play all 16."
Schwartz acknowledged there's a difference between a player practicing hurt and avoiding turning something little into a major setback, especially before the regular season.
"We're in preseason where you have guys that could potentially go, but sometimes it just doesn't make a lot of sense," he said. "Some guys try to rush back and end up setting themselves back. It's a difficult situation. Guys are competing for jobs. Guys want to go out and practice with their teammates. Sometimes, it makes a little more sense to hold them another day or a week."
Copyright 2011 by The Associated Press