The league plans to move the game to Monday or Tuesday, which will provide time for more tests.
The Titans returned eight positive tests after playing the Minnesota Vikings in Week 3, three of which belonged to players. A fourth player tested positive Tuesday.
Tennessee was forced to shut down its facilities in an effort to halt the spread, thereby also impacting the team's ability to prepare for the game.
As of Tuesday evening, Steelers head coach Mike Tomlin said he was under the impression the game would proceed Sunday as scheduled.
"We've been given a mandate to prepare as if the game is going to be played and played on time, and so that is our mentality," he told reporters. "We've gone about today's business from a game-planning standpoint with that mentality, and we intend to push into tomorrow with a normal schedule."
The Titans and Steelers are both 3-0, making their Week 4 matchup one of the most intriguing games on the schedule.