"They're both banged up, like a lot of guys on our team," Hitchcock said after neither St. Louis forward took part in the team's morning skate at Canadian Tire Centre.
Schwartz and Sobotka played Saturday in the Blues' 4-3 overtime win against the Columbus Blue Jackets that began their two-game road trip.
"We went the other way against Columbus and neither guy was effective in the tail end of the game," Hitchcock said. "It's not starting the game, it's finishing the game. And for us, if we feel like we want them to finish the game, then we're going to have to give them as much rest as we can so that they're ready to go, so we opted not to skate them [Monday]."
"Quite frankly we weren't playing very good," Hitchcock said. "We weren't playing very good defensively and we needed to make some adjustments."
"We've got to get more continuity and better play back there," Hitchcock said. "Our transition game from our exits was too inconsistent. That's the first game in a long time where we've given the puck away, turned it over and created odd-man scoring chances-against because of it. Once we settled down and started to play the right way on our exits we started to get better, and I thought changing the pairs up gave them a different focus and we'll probably continue down that path [Monday]."
Hitchcock was direct in explaining his decision to dress Colaiacovo instead of Cole: "Better puck movement, better transition, less big errors."
Ottawa defenseman Jared Cowen returns after serving a two-game suspension for his hit to the head of the Buffalo Sabres' Zemgus Girgensons on Tuesday, but Marc Methot will miss his third game in a row.
Methot practiced with his teammates Monday, but Senators coach Paul MacLean prefers to be cautious after the 6-foot-3, 230-pound defenseman missed the past two games with an illness.
"He lost a ton of weight being sick twice and we want to make sure that he's ready to go," MacLean said.
Rookie defenseman Cody Ceci will make his third straight start.
Here are projected lineups for the Blues and Senators: