Clifford said there is a chance that Jefferson could play in Game 5, but the Bobcats need to win on Monday night first. Miami leads the best-of-seven series three games to none.
Bismack Biyombo will start in the place of Jefferson.
Jefferson, who led the team in scoring and rebounding this season, strained the plantar fascia in his left foot in the first quarter of Game 1.
The Bobcats were 5-4 when Jefferson didn't play this season. Clifford said if this was the regular season, Jefferson would be out two to three weeks.
"I wouldn't wish this pain on anyone," Jefferson said. "It's the worst pain I've ever dealt with in my career. I'm seeing how it's going to feel and go from there."SI.COM STAFF: Playoff roundtable: Which No. 1 seed is at more risk of upset: Pacers or Spurs?