Mack (hamstring) returns to Colts practice

The Indianapolis Colts' top running back is making his way toward a return.

Marlon Mack was back at practice for the first time in almost a month on Thursday. The shifty back has been dealing with a hamstring injury since exiting the team's first preseason tilt on Aug. 9.

The Colts haven't pushed the second-year back, fearing the soft-tissue injury could linger longer if tested before he's ready.

Thursday's return to practice is a positive sign Mack will be back early in the season, but beat reporter Zak Keefer of the Indianapolis Star cautions the running back remains a long-shot to play in Sunday's season opener versus the Cincinnati Bengals.

Mack's injury put a damper on the Colts' backfield optimism after the team parted ways with veteran Frank Gore this offseason. Following an up-and-down rookie campaign in which Mack flashed big-play ability, Colts owner Jim Irsay boasted that the running back could approach 1,500 yards in 2018.

Jordan Wilkins, Nyheim Hines and Christine Michael have handled the running back duties with Mack on the sidelines. Wilkins has shown flashes of playmaking ability and owns the highest upside of the trio. Mack should jump back to the top of the group when he's fully cleared.

The Colts received more positive injury news, as left tackle Anthony Castonzo (hamstring) said Thursday that he is optimistic he could play Sunday.