PEORIA, Ill. (AP) – Cubs pitcher Mark Prior struggled to get out of the second inning of his rehab appearance Monday for Chicago’s Class A affiliate, the Peoria Chiefs.

The 25-year-old right-hander threw 44 pitches in two innings, giving up four hits and three runs. He’s been on the disabled list all season as he works his way back from a sore shoulder.

“You can only do so much,” Prior said. “I’ve been doing everything I possibly can every day and I just have to let nature take its course.”

After a solid first inning, trouble came with one out in the top of the second when Kane County’s Jose Pineda homered to left.

Prior felt he improved his mechanics.

“In these type of situations you’re looking more for how your execution was, not so much what the outcome is,” Prior said. “My main priority was to throw strikes and get ahead of guys predominantly with fastballs.”

Prior struck out three. His fastball reached 90 mph against the final batter he faced.

It is not certain when Prior will pitch again, but it is likely he could make another start before June 5, when the Chiefs’ nine-game homestand ends.

AP-ES-05-29-06 2125EDT