Casey Mize’s return to game action was a brief one thanks to one long inning. The top pitching prospect in MLB Pipeline’s Top 100 left in the first inning of what was essentially a rehab start for Class A Advanced Lakeland Wednesday night.

Though the quick exit raised worries about a possible setback in his return from shoulder fatigue, the move was due to a long inning based on organizational policy. There were no health issues, according to two organizational sources.

Mize, the Tigers’ top prospect according to MLB Pipeline, retired Bradenton’s first two batters, including a strikeout of leadoff batter Oneil Cruz, before Pirates No. 3 prospect Travis Swaggerty completed an eight-pitch battle with a ground-rule double to left-center at Joker Marchant Stadium.

Mize walked the next two batters, both on 3-2 pitches, before he was pulled. He threw 32 pitches, just 17 for strikes, but he reportedly threw all of his pitches. His fastball sat at 93-95 mph, according to a source.

Mize was expected to throw around 60 pitches or four innings in the start after throwing 45 pitches in a camp game five days earlier. Once it was determined he felt fine, he went to the bullpen to complete his pitch count, finishing with 64 pitches.

Mize’s return came four weeks after he left a start for Double-A Erie in the third inning with what was determined to be shoulder fatigue. The injury raised alarms for fans and officials alike, but tests confirmed he had no structural issues in his shoulder. After consulting with noted orthopedic surgeon Dr. James Andrews, Mize went on a strengthening program in Lakeland, Fla.

The hope was that Wednesday’s outing would allow him to return to Erie next week, joining Futures Game participant Matt Manning, fellow first-round pick Alex Faedo and recently-promoted Tarik Skubal in a star-studded SeaWolves rotation. With Wednesday’s early exit, however, Mize is expected to stay in Lakeland and make another start for the Flying Tigers next week. The team is off next Monday but has a doubleheader scheduled the following night in Dunedin.