The goalie did not dress for a 2-0 home win against the Calgary Flames on Saturday, when Jack Campbell made 31 saves.
Michael Hutchinson
was the backup.
Andersen did not practice Monday and is not expected on the ice Tuesday, Keefe said.
The Maple Leafs are scheduled to play at the Ottawa Senators on Thursday (7 p.m. ET; TSN5, RDS, TSN4, NHL.TV).
"Just lower body," Keefe said. "Same thing that he missed time for previously. Nothing new."
Andersen missed four games from Feb. 22-March 1. He made 26 saves in a 6-1 win at the Edmonton Oilers on March 3 and did not play at the Vancouver Canucks the next night. He then played the next six games, going 1-5-0 with 3.84 goals-against average and .862 save percentage.
Campbell also did not practice Monday, but Keefe said the Maple Leafs wanted to give him an extra day of rest because he has been dealing with a lower-body injury of his own this season. He's 4-0-0 with a 1.00 GAA, .956 save percentage and two shutouts in four games. He made 30 saves in a 4-0 win at the Oilers on Feb. 27 and hasn't allowed a goal since a 3-2 win at the Flames on Jan. 24.
"He's been tremendous," Maple Leafs forward William Nylander said. "I know that he's been struggling with an injury. You can see the resilience when he's working every day in the gym, rehabbing his injury and getting back out there and being a dominant goalie."
Maple Leafs defenseman Morgan Rielly lauded Campbell's attitude.
"He works hard," Rielly said. "He's an extremely good teammate and players just like being around him just because of who is as a person. I think that's the most important thing. He brings that attitude every day where he's going to work hard and he's just going to be a part of the team no matter what. I think that's a great person to have your side. We're happy to have him and he's playing well for us."
