The Milwaukee Brewers placed rookie left-hander Robert Gasser on the 15-day injured list Wednesday due to a left flexor strain.

The move is retroactive to Sunday. In other moves, the Brewers recalled right-hander Tobias Myers and left-hander Aaron Ashby from Triple-A Nashville, and optioned RHP Janson Junk to Nashville.

Ashby is scheduled to start for the Brewers on Wednesday afternoon against the host Philadelphia Phillies.

Gasser experienced tightness and soreness after his last appearance on Saturday, when he went five innings and allowed three runs and seven hits in a 4-3 win against the Chicago White Sox.

Gasser, who turned 25 last Friday, is 2-0 with a 2.57 ERA over five starts since his major league debut on May 10. The Brewers' No. 4 prospect, according to MLB Pipeline, Gasser started the minor league season on the injured list after dealing with bone spurs in his elbow during spring training.

Gasser reportedly will seek a second opinion from Neal ElAttrache on the injury.

Ashby, 26, is 0-1 with a 9.82 ERA in one start for Milwaukee this season.

Myers, 25, made his major league debut on April 23 and is 1-2 with a 5.40 ERA over seven games (six starts).

Junk, 28, is 0-0 with a 9.00 ERA over three relief appearances.