James has been dealing with a left ankle sprain since Sunday and Davis hasn't played since Feb. 16, when he suffered a right midfoot sprain.
With Tuesday's defeat, the Lakers (31-44) are now tied with the San Antonio Spurs for the final play-in spot in the Western Conference with seven games remaining for both teams.
"We identified right before that Pelicans game [Sunday] that these are our playoff games," Lakers coach Frank Vogel said before Tuesday's game. "The playoffs start for other teams when the actual regular season ends, but every game matters for us right now so there's a playoff-series element to these final games.
"And you start talking about what the mindset is. The intensity is a notch higher. The focus has to be a notch higher. Every possession matters. No techs. No delay of games. You have to get every loose ball. You have to execute every coverage that's controllable. All those things that go into competing in a playoff series, we talk about those things with our guys in the group."
Vogel said both players would be reevaluated on Thursday to determine if they can play against the Utah Jazz on Thursday night.
The Lakers trailed the Mavs 82-56 at halftime, representing the most points the team had given up in a half since the franchise moved to Los Angeles.