Morrow pitched a scoreless first inning against Northwest Arkansas, then allowed three runs in the second. He would leave in the third inning after getting two outs. Morrow threw 49 pitches (32 for strikes); he was expected to throw around 80 pitches.
Morrow allowed three runs on eight hits with one walk and three strikeouts in 2 2/3 innings. In his first rehab start with the Missions, Morrow threw 54 pitches over four scoreless innings on June 2.
Morrow was 2-0 with a 2.73 ERA in five starts with the Padres when he landed on the DL last month.
He was in line to possibly come off the DL for a start Friday at Petco Park against the Dodgers, but Odrisamer Despaigne -- who got the loss Sunday against the Reds and has replaced him in the rotation -- will likely remain in the rotation if Morrow isn't ready.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.