BOSTON (CBS) — The season just got even more difficult for the 1-2 New England Patriots.

The team placed running back Rex Burkhead and rookie linebacker Ja’Whaun Bentley on injured reserve.

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Burkhead suffered a concussion during Week 1’s win over the Texans, and he left the team’s Week 3 game in Detroit early due to a neck injury.

Bentley’s injury is not yet disclosed. The 22-year-old linebacker was selected with the 143rd overall pick (fifth round) of April’s draft. He’s been heavily involved in the Patriots’ defense through three weeks, taking 69 percent of the team’s defensive snaps in Week 1, 42 percent in Week 2 and 78 percent in Week 3. In Sunday’s loss to the Lions, he came up with one of the few positive plays for the Patriots’ defense when he intercepted a Matthew Stafford pass early in the third quarter. He recorded 13 total tackles (eight solo tackles) in the three games.

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Burkhead, 28, joins fellow running back Jeremy Hill on the injured reserve list, leaving the Patriots with just James White and Sony Michel left as primary backs. The team did re-sign running Kenjon Barner on Wednesday, though he’s more of a punt returner than he is a traditional NFL running back.

The moves to IR do not necessarily end the season for Burkhead or Bentley. NFL rules allow for teams to activate two players from IR in a season, once those players have been on IR for eight games.

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In addition to Burkhead, Bentley and the aforementioned Hill, the Patriots’ IR list includes WR Braxton Berrios, CB Duke Dawson, TE Ryan Izzo, OL Ulrick John, LB Christian Sam, and OL Isaiah Wynn. The injuries to Hill and Wynn were season-ending.