Semien will take over for Gordon Beckham, who all but certainly will start on the disabled list due to a strained left oblique. Beckham is eligible to return on April 5, with Semien most likely moving to a utility role.
That switch presents a part-time playing challenge for the 23-year-old, who has started in his three previous Minor League seasons. But it's one where Semien already has mapped out a plan.
"You have to prepare yourself every day to be ready for any situation," Semien said. "That means in BP, you have to put yourself in some game situations. Work hard defensively at all three positions. Watch a lot of video [of pitchers]. It's a lot of mental preparation and watching from the sidelines.
"I've been watching Gordon in BP and he's getting better every day swinging the bat. He's actually swinging the bat really well. I know he's progressing well. I know once he comes back, that's his spot. He's the second baseman here in Chicago. I'm filling in. I don't know what's going to happen once he comes back. I'll be prepared for anything."
Scott Merkin is a reporter for MLB.com. Read his blog, Merk's Works, and follow him on Twitter @scottmerkin. This story was not subject to the approval of Major League Baseball or its clubs.