Pittsburgh Steelers running back Le’Veon Bell underwent surgery Monday on a core muscle injury, NFL Network’s Ian Rapoport reports, citing a source.

He’s expected to require six weeks to recover.

A groin injury sidelined the star running back six carries into the AFC Championship Game against the New England Patriots in January, which the Steelers went on to lose 36-17.

The Steelers were aware of the injury, which occurred late in the regular season, but it was reported in February that Bell wasn’t expected to require surgery.

Despite playing in just 12 regular-season games, Bell finished fifth in the league in rushing yards with 1,268. He added 616 receiving yards and nine total touchdowns.

The Steelers used their franchise tag to retain Bell for one more season and are reportedly in talks for an expensive long-term contract.

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