Contreras has appealed the suspension, so he was in the lineup for Saturday's second game of the three-game series.
Contreras and Lackey were ejected in the fifth inning a day earlier for arguing with home plate umpire Jordan Baker. Lackey thought St. Louis pitcher Carlos Martinez struck out to end the inning, but the pitch was called a ball. Martinez then singled to drive in a run, giving the Cardinals a 2-1 lead.
Lackey argued and was ejected. Contreras was ejected a short while later and threw down his mask in anger. It bounced up and hit Baker's leg.
Contreras, 25, apologized after the game, saying he had no intention of hitting Baker. Maddon is hoping Contreras' postgame comments will be a factor in possibly reducing the suspension.
"He's a wonderful young man," Maddon said. "He is emotional. We're all working to help him curb that a bit, but you don't want to take it all away. That's a big part of why he's so good."
Lackey, 38, wasn't contrite after the game.
"It's a pretty big spot right there," he said. "It cost me a big league win. Those don't grow on trees."