Brown hasn't played since he suffered a calf injury during a Week 15 loss to the New England Patriots.
Katherine Terrell of ESPN.com reported he missed practice Friday because of an illness.
Still, head coach Mike Tomlin didn't seem particularly concerned, saying, "I think we've all seen Antonio play enough that we know what he's capable of."
"It's the playoffs—you've got to do whatever it takes," Brown said, according to Jeremy Fowler of ESPN.com.
Brown can do whatever it takes better than almost any player in the league. He was an MVP candidate throughout the 2017 campaign and led the NFL with 1,533 receiving yards despite playing just 14 games. He also made 101 catches and nine touchdown receptions on his way to his sixth career Pro Bowl selection.
His presence will be key as the Pittsburgh aerial attack looks to beat a Jaguars defense that intercepted Ben Roethlisberger five times during Jacksonville's 30-9 win in Week 5. While Brown played well with 10 catches for 157 yards, he will have his hands full against cornerback Jalen Ramsey on Sunday.
If they win, Brown and the Steelers will then be tasked with a matchup against the defending Super Bowl champion New England Patriots in the AFC title game.