CHARLOTTE, N.C. -- The Carolina Panthers on Saturday activated running back Christian McCaffrey from injured reserve, making him eligible for Sunday's home game against the New England Patriots.

Also, quarterback Sam Darnold was cleared from the concussion protocol, but he continues to deal with a shoulder injury that keeps him questionable for the 1 p.m. ET game.

Coach Matt Rhule said on Friday that Darnold possibly could back up P.J. Walker, who has taken most of the first-team reps in practice, if he doesn't start. There is concern the shoulder isn't strong enough for Darnold to throw deep.

Being activated doesn't mean McCaffrey, who has missed five games with a hamstring injury, will play. The staff will evaluate him again on Sunday morning to make sure there have been no setbacks.

If McCaffrey plays, he is expected to be on a pitch count that likely would limit him to fewer than 30 to 40 snaps. Rhule wants to keep rookie Chuba Hubbard, Royce Freeman and Ameer Abdullah, who helped the Panthers rush a season-high 47 times for 203 yards last week at Atlanta, in the mix.

Hubbard has been the starter in McCaffrey's absence, but Rhule said Abdullah in particular added a "jolt'' to the running game against the Falcons.

"Really twitchy, fast,'' Hubbard said of Abdullah. "Can make a guy miss in a phone booth.''

McCaffrey injured his hamstring in the second quarter of a Week 3 win at Houston. He appeared set to come back two weeks later, but after practicing on a limited basis four times over two weeks, he was placed on injured reserve.

He has missed 18 of 24 games because of injury since Rhule was hired last year. Darnold suffered both of his injuries with just under seven minutes left in the 19-13 win at Atlanta on a first-down run around the left side.

"Our job is to prepare for all contingencies and expect the unexpected,'' Rhule said.

If Walker starts, it will be his second in the NFL. Last year, he threw for 258 yards and a touchdown in a 20-0 victory over Detroit in replacing the injured Teddy Bridgewater.