Lugo injured his left quad on the play, slowing just steps before crossing first base and immediately falling to the ground after safely crossing the bag. Manager Terry Francona said after the game that the leg would need to be evaluated, but early indications didn't leave him incredibly optimistic.
"His quad, I think he did it pretty good," Francona said. "We'll get him looked at tomorrow, but I think there's a chance that he didn't just strain this."
Lugo was not available after the game, but teammate and fellow middle infielder Dustin Pedroia said that he was in good spirits.
"He's OK," Pedroia said. "There's always a lot of energy out of Lugie. He'll be all right."
Lugo wasn't the only Boston infielder to feel discomfort after a play at first. Kevin Youkilis grounded out to Baltimore third baseman Melvin Mora to end the seventh inning, then took his time taking his position on the field.
"[My] hamstring tightened up," Youkilis said. "Little cramping, but that's about it."
Lugo wasn't as fortunate. Alex Cora pinch-ran for Lugo, and if Francona's initial worries are confirmed, Cora will likely get the start at shortstop on Saturday night against the Orioles.
Mark Remme is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.