Patriots running back Dion Lewis is reportedly going under the knife for a second time on his knee and is out "indefinitely" according to Jim McBride of the Boston Globe.

Lewis tore his ACL back in November after emerging as a dynamic rushing and receiving threat in the Patriots' up-tempo, short-passing offense.

Lewis was expected to return for the start of the regular season, but that's out the window now.

McBride reports a "timetable for his return is uncertain," while Adam Schefter of ESPN reports Lewis is out "indefinitely" but could still return this season.

Tom Curran of CSNNE reports the surgery "does not involve the ACL" -- it's believed to be a "clean up" surgery as a follow up to the initial procedure.

Lewis' development last year was fascinating. He was drafted in the fifth round out of Pittsburgh by Andy Reid and the Eagles in the 2011 NFL Draft but never produced much on the field, rushing 36 times and catching three passes over two years. He latched on with New England and became a perfect fit in the Pats offense as a duel-threat offensive weapon who had joystick-like juke moves.

He rushed 49 times and averaged 4.8 yards per carry and caught 36 passes while averaging 10.8 yards per catch over the course of seven games, helping to make the Patriots offense even more dangerous by leveraging defenses in a different way. (Watch Rob Gronkowski streaking up the seam and Lewis will torch you short. Good luck ignoring Gronk.)

When he went down, the Pats offense suffered as well.

The Pats averaged 34.5 points per game with Lewis in the lineup and averaged 23.6 points per game after Lewis went down.

The most likely situation for New England now is James White takes over in the Lewis role, catching passes and doing a poor man's Dion impression. LeGarrette Blount continues in his role as the short-yardage hammer who gets featured when the Patriots spot a soft rush defense on the schedule.