MESA, Ariz. -- Cubs pitcher Jake Arrieta is inching closer to throwing off the mound.
The right-hander, projected as one of the club's starters, has been slowed this spring because of tightness in his right shoulder. He will have a flat-ground session on Saturday, and the Cubs will decide if he's ready to take that next step and get on the mound after that.
"We're going to take it day by day," Arrieta said Friday. "Every day's been good. It's gotten progressively better. If we stay on the same schedule, I'm optimistic I'll be ready by Opening Day."
Arrieta has competition for the rotation. The Cubs signed free agents Jason Hammel and James McDonald and also have lefty Chris Rusin in the mix.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.