The shortstop was not in the starting lineup for the series opener against the Royals, which the Red Sox lost, 8-6, but Francona said before the game that Lugo would be available off the bench.
"[The situation] is not less serious today," Francona said, "but he needed to be with his wife last night."
Lugo is the second Boston player to miss a game this week because of a family matter, as second baseman Dustin Pedroia did not play on Monday against Oakland. Pedroia's wife, Kelli, is pregnant, and was taken to an area hospital after going into labor earlier than expected.
John Barone is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.