Zack Greinke‘s first platelet-rich plasma injection worked.

Tomorrow, six days after he received the PRP shot to treat inflammation in the back of his right elbow, Greinke could throw a light bullpen session at Camelback Ranch, Dodgers manager Don Mattingly said.

“He’s good today,” Mattingly said. “Sounds like he’s encouraged. Stan (Conte, the Dodgers’ vice president of medical services) felt like (Greinke) was encouraged after he threw.”

Greinke began throwing from flat ground Friday and threw again Saturday morning.

“He played (catch) already,” Mattingly said. “He felt good today. He feels good. We’ll see where he’s at tomorrow.”

Initially, the team indicated that Greinke’s first bullpen session would have to wait until next week. If you believe the week begins on Sunday, Greinke is right on time; if you believe it begins on Monday then he’s slightly ahead of schedule.