CHARLOTTE, N.C. (AP) — Panthers quarterback Cam Newton was not at the start of practice for the second straight day while dealing with a concussion.

Derek Anderson continues to take first-team reps, with Joe Webb the backup. Anderson is 2-0 as a starter since coming to the Panthers as a free agent in 2011. Both wins came against the Tampa Bay Buccaneers, whom the Panthers host Monday night.

Newton, the 2015 league MVP, has taken several shots to the head this season, including four in the season opener against the Denver Broncos.

But it was a hit Newton took from Atlanta’s Deion Jones on a 2-point conversion run this past Sunday that finally drove him from a game. Newton left early in the fourth quarter of Carolina’s 48-33 loss at the Georgia Dome.

The 33-year-old Anderson relieved Newton and threw two touchdowns to get Carolina back in the game before two interceptions in the closing minutes.

The Panthers (1-3) are confident Anderson can get the defending NFC champions back on track. Carolina has lost two straight and is two games behind the Falcons in the NFC South, a division it has won the past three seasons.

Newton was among four players not present for the first 20 minutes of practice Thursday that are open to the media. Left tackle Michael Oher (concussion), cornerback James Bradberry (toe) and defensive tackle Vernon Butler (ankle) were also no-shows. Linebacker Thomas Davis and running back Jonathan Stewart, who are battling hamstring injuries, were at practice but not in pads.

If Oher can’t play, the Panthers will again move Mike Remmers to left tackle and start Daryl Williams at right tackle against the Bucs (1-3).

Stewart has missed the last two games with a hamstring injury. Cameron Artis-Payne will split carries with change-of-pace back Fozzy Whittaker if Stewart remains out of action.

Bradberry, the team’s top draft pick this past season, has struggled a bit in pass coverage. Matt Ryan threw for 503 yards and Julio Jones had 300 yards receiving last Sunday against the Panthers young secondary that lost All-Pro Josh Norman in the offseason.