O'Neill (elbow) will begin a rehab assignment at Double-A Springfield on Tuesday, Rob Rains of StLSportsPage.com reports.

EDGE Analysis

O'Neill was placed on the 10-day injured list April 16 with a right elbow nerve subluxation, but his ability to resume action in the minor-league ranks a week later suggests the issue isn't a serious concern. The 23-year-old may only stick with Springfield for a couple games before rejoining the Cardinals for their weekend series with the Reds.