By Bruce Levine–

GLENDALE, Ariz. (CBS) — What appears to be the great unknown in relation to the health of the White Sox bullpen didn’t get any clearer Saturday.

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Manager Robin Ventura couldn’t say for sure when closer David Robertson and setup man Jake Petricka would be available to turn it up for Opening Day on April 6.

Robertson and Petricka are both dealing with ailing forearm issues, according to the White Sox. Petricka played catch Saturday and said he will build up his strength from this point on, but he also had no idea when a side session would be scheduled. Robertson is scheduled to pitch Sunday, but that isn’t a certainty at this time.

“Today he was lightly tossing,” Ventura said of Robertson. “He is still supposed to pitch. We are being extra cautious with him. He does not seem to be concerned.”

Replacements for the two back-of-the-bullpen pitchers are there in numbers, if not experience.

“Every time you get closer (to the season) it becomes more of a concern,” Ventura said. “With this, you want to be sure to be cautious enough. We want to make sure we don t have any setbacks.”

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When asked directly who would be candidates for the roles of Robertson and Petricka, Ventura was purposely vague.

“Other pitchers,” he responded.

“The ones in that room — that is where they will come from.”

Neither Robertson nor Petricka will be going to Kansas City in nine days unless they get up on a mound in the next week, face live hitting and come out of it feeling well.

“With Robbie and Jake, you are going to want to see them in a game,” Ventura confirmed. “You will want to see them pitch and check them out. There are only so many guys we have. I am going to put somebody in there.”

In other news Saturday, the White Sox optioned right-handed Daniel Webb to Triple-A Charlotte and reassigned left-hander Zach Phillips to minor league camp.

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Bruce Levine covers the Cubs and White Sox for 670 The Score and CBSChicago.com. Follow him on Twitter @MLBBruceLevine.