Yu Darvish felt soreness in his troubled triceps tendon after a minor league rehabilitation start Monday night.

Darvish hasn't pitched for the Chicago Cubs since May 20. He threw five sharp innings for Class A South Bend.

"In the triceps there's likeliness to get more fatigue there, especially if there's a long gap between innings," Darvish said through a translator. "That's when I feel fatigue there. Not necessarily pain, but I can't for sure say there is nothing going on in the tricep zone."

Darvish, who pitched a simulated game last week in Chicago, was set to rejoin the Cubs in Los Angeles on Tuesday. He said his performance was "not perfect."

I will be flying into L.A. and we'll be discussing more about the future schedule," Darvish said. "It's not up to me to decide. The coaches and manager will have to watch the [rehab] game and decide. It's not anything bad. Anyone comes off DL goes through this."