Paul suffered a left groin strain in Phoenix's 97-87 loss in Game 2 at Denver on Monday, which gave the Nuggets a 2-0 edge in the Western Conference best-of-seven series.
Reserve guard Cameron Payne is expected to replace Paul until the 37-year-old Paul, a 12-time All-Star, returns to duty.
"You can't replace what Chris brings to the team," Suns star Devin Booker said. "He'll still be there, being a leader, being vocal.
"The things he does on the court, we're just going to have to find other ways to be effective."
Paul averaged 13.9 points, 8.9 assists, 4.3 rebounds and 1.5 steals a game for the Suns this season.
The Suns went 45-37 this season to finish fourth overall in the West and eliminated the Los Angeles Clippers in five games in the opening round of the NBA play-offs.
