Marshall missed Denver's practice Thursday after suffering a hamstring injury a day earlier.
"Coach never played in the NFL," Marshall was quoted by Fox Television affiliate KDVR-TV in Denver as telling reporters after the decision. "I'm going to handle this professionally."
McDaniels added several others will play Sunday with worse injuries.
Marshall leads the Broncos with a career-high 10 touchdowns on 101 receptions for 1,120 yards, including an NFL record 21 receptions for 200 yards with two touchdowns in a Dec. 13 loss at Indianapolis.
Denver needs a win in the regular season finale plus help in other games involving AFC contenders to qualify for the AFC playoffs.
"Our word this week has been accountability," Daniels said. "We're looking for the 45 guys who want to help us win and make the playoffs. Anyone who doesn't, well play without 'em."
"I played last year with a tear in my hip, so I don't think my toughness is in question here," Marshall said.