The power-hitting rookie popped up to end the sixth and was removed immediately after the at-bat. Trumbo, who was 0-for-3, said he felt "a little banged-up" but was hopeful that with treatment, he'd be healthy for Sunday's series finale.
Manager Mike Scioscia said the ankle injury has been bothering Trumbo for most of the second half. Trumbo may have aggravated the injury in the third inning after recording all three putouts on ground balls hit his way. He seemed to pull up after racing to the bag to get Josh Willingham for the third out.
"I don't know if it was any one thing," Scioscia said. "All these guys have a lot of mileage on them this year. It's getting late, and Mark's played a lot."
Even a short-term injury to Trumbo, a key bat in the middle of the order, would hurt the Angels, who are battling Boston and Tampa Bay for the Wild Card and the final spot in the American League playoffs.
Trumbo leads the Halos with 29 home runs and 87 RBIs. The last rookies to lead their respective teams in homers and RBIs are Jody Gerut with Cleveland in 2003 and St. Louis slugger Albert Pujols in '01.
Trumbo is also one home run shy of becoming the seventh rookie in the last 25 years with at least 30 home runs in a season.
Trumbo and closer Jordan Walden, who has 32 saves, could become the first rookie tandem in Major League history with 30 home runs and 30 saves, respectively.
A.J. Cassavell is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.