Phoenix interim coach Jay Triano said Monroe would start in place of Chandler, in part to keep the second unit of the Suns intact.
Triano deemed Monroe, who was traded from the Milwaukee Bucks in the Eric Bledsoe deal, ready to play against the Houston Rockets after discussing the Suns' offensive sets with him before the game.
"The playbook will be restricted obviously," Triano said. "But he's got more games under his belt than the rest of our lineup, so I'm sure he's going to figure things out."
Chandler will not play against Rockets or join the team on its trip for Friday's road game against the Los Angeles Lakers. He has a respiratory illness that is contagious.
Chandler is averaging 7.0 points and 9.5 rebounds for the Suns this season.
Monroe has career averages of 14.0 points and 8.7 rebounds but played sparingly for the Bucks this season before being traded.