Lopez underwent a precautionary MRI on his foot on Monday in New York that came back negative. Lopez, who missed practice Monday, remains day to day.
"We'll see how he moves around and continues to progress," Johnson said, "But at some point, he'll have to practice before we stick him in a game."
The Nets also will be without power forward Reggie Evans (flu) against the Thunder. Evans averages a team-leading 8.4 rebounds per game.
Asked if Lopez would be ready for Friday night's game against the Golden State Warriors, Johnson replied, "We don't have a sense yet. Let's just see how he progresses."
Lopez, 24, had missed the past two games with a sprained right foot. He suffered the injury in the third quarter of Wednesday's victory over the Boston Celtics.
The center has already undergone a battery of tests that determined this injury is unrelated to the two right foot fractures that caused him to miss all but five games last season.
Lopez is averaging 18.5 points, 6.8 rebounds and 2.5 blocks per game for the Nets (11-4).
Backup Andray Blatche has started the past two games in place of Lopez and has averaged 17 points and 8.5 rebounds on 53.8 percent shooting.
Mike Mazzeo is a frequent contributor to ESPNNewYork.com.