Matthews was a game-time decision after he was on the ice with Toronto's extra skaters earlier in the day. The Maple Leafs did not have a full morning skate.
Matthews missed a 4-0 win against the Oilers on Saturday but practiced Sunday.
"He's progressed here today compared to where he's been in the last few days," Keefe said Sunday. "That's very positive here. He's not ruled out for tomorrow. We're just going to have to see how he is."
Keefe said Matthews was limited in drills and did not skate on a regular line.
Matthews leads the NHL with 18 goals and has scored 31 points in 20 games.
Goalie Frederik Andersen practiced Sunday, but he is out a fourth straight game Monday with a lower-body injury.
"His injury, basically where we're at here now is waiting for him to be comfortable," Keefe said. "Today, he was on the ice for the better part of an hour and took lots of shots, so we're essentially just waiting for him to feel comfortable. We don't really know when that's going to be, but today was a very positive step towards that.
"Whether it's goaltending or it's Auston up front or some of our other situations, we've got a lot of question marks that probably won't get answered until game time tomorrow."
Michael Hutchinson was in the starter's net during the optional morning skate. Jack Campbell returned Saturday and made 30 saves for the shutout. He was out 14 games with a leg injury and did not practice Sunday.
The Maple Leafs (16-4-2) are first in the Scotia North Division, six points ahead of the Oilers and seven ahead of the third-place Winnipeg Jets. After Monday, they will play at Edmonton on Wednesday before finishing a five-game road trip with two at the Vancouver Canucks on Thursday and Saturday.
