Red Sox manager Terry Francona -- according to club spokesman Henry Mahegan -- confirmed to reporters in Toronto that Lugo wasn't with the club, but chose not to get into any details.
Shortstop Jed Lowrie appears poised to be activated from the disabled list on Saturday. Third baseman Mike Lowell could return by Friday. This means that the Sox need roster spots.
Because of Nick Green's emergence from non-roster invitee to key contributor and Lowrie's imminent return, the Red Sox essentially don't have a spot for Lugo.
The Red Sox have put feelers out for a potential trade partner for Lugo, though they'd likely be on the hook for the roughly $13.5 million the shortstop is owed through the end of 2010. If a trade can't be worked out within the next day or so, the Red Sox could designate Lugo for assignment, paving the way for his ultimate release.
Will the Red Sox eat the remainder of Lugo's salary?
"We will do what is in the best interests of the club ... in all matters," Red Sox principal owner John W. Henry wrote in an e-mail to the Boston Globe on an inquiry that was specifically about Lugo.
Such a situation would have seemed unthinkable in December 2006, when the Red Sox signed Lugo off the free-agent market for four years at $36 million.
Originally signed to be the club's leadoff hitter, Lugo struggled early in his first season and never fully rebounded to be the sparkplug the Red Sox remember playing against with the Tampa Bay Rays. Lugo has batted in the bottom portion of the order during most of his time in Boston. But the bigger issue has been his defense.
After making 16 errors in the first half of the 2008 season, Lugo tore his left quad and missed the entire second half.
He came to Spring Training this season eager to try to reclaim his job in a position battle with Lowrie. But that plan ended when Lugo, 33, had to undergo right knee surgery in March.
Though Lowrie had to undergo left wrist surgery in April, Lugo couldn't capitalize on the opening once he returned to the roster on April 27.
His range seemingly limited from his leg woes, Lugo was supplanted by Green for good in late May.
Playing in 37 games this season, Lugo is hitting .284 with one homer and eight RBIs. He has seven errors in 97 total chances.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.