Dodgers starter Zack Greinke, on the 15-day disabled list, began his rehab assignment with Class A Rancho Cucamonga Friday.

Greinke ran into some trouble, as his defense committed three errors. The right-hander allowed eight runs -- three earned -- and six hits over 4 1/3 innings of work. He struck out four and did not issue a walk in 80 pitches, 54 strikes.

The 29-year-old remains hopeful of joining the rotation Wednesday against the Nationals at Dodger Stadium.