Indianapolis Colts running back Marlon Mack left Sunday’s 27-20 loss to the Jacksonville Jaguars with a potential season-ending Achilles injury.

Mack started the season on top of the Colts’ depth chart at running back. He ran four times for 26 yards on Sunday before leaving the game. He led the Colts in rushing last season with 1,081 yards and eight touchdowns.

Rookie Jonathan Taylor up next?

The Colts selected Wisconsin running back Jonathan Taylor in the second round of April’s draft. They intended to keep Mack as the starter and listed him at the top of their initial depth chart, with head coach Frank Reich saying this summer that he would take a “hot-hand” approach to divvying up carries.

It appears that Taylor will now be thrust into a primary role and share carries with third-year pro Nyheim Hines.

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