Lucas Giolito, the nation's No. 1 right-handed pitching prospect, won't throw for a month and could be out of action up to 10 weeks after spraining the ulnar collateral ligament in his right elbow. The Harvard-Westlake (Studio City, Calif.) senior left his start Tuesday afternoon with one out in the seventh inning.

"He felt something yesterday, but he feels fine right now," Harvard-Westlake coach Matt LaCour said. "I think it's hard for him to fathom that he’s not healthy enough to pitch, but this is a situation where you absolutely do what the doctor says. It’s not tragic in terms of Lucas' future in baseball, but it may mean that he doesn't pitch for us again this season."

The 6-foot-6, 240-pounder hit 100 on the radar gun twice in his start on Feb. 28. Giolito is vying to be the first right-handed high school pitcher selected No. 1 in the MLB draft. He has signed with UCLA, and it's too early to tell how his draft stock will be affected by this setback.

"We've discussed a plan for him going forward," LaCour said. "We'll get him pretty active starting next week. We'll be aggressive and try to get him better in other areas, try to strengthen his body in some other areas aside from his arm. He still wants to work on getting better every day."