The Pirates placed Lyles (side) on the injured list Thursday.
Pittsburgh isn't expected to need a fifth starter -- Lyles' expected role -- until late next week. He is symptom-free but still building up his workload. The expectation is that he will throw a six-inning, 100-pitch sim game later this week and if all goes well he will take the ball April 7 against the Reds. Lyles, a free agent acquisition, registered a 5.06 ERA and 1.55 WHIP in 16 spring innings.