HOUSTON -- Carolina Panthers running back Christian McCaffrey suffered a hamstring injury in the second quarter of Thursday night's game at Houston and will not return.

The injury occurred when McCaffrey was making a run to the left on first-and-10 from the Texans' 14-yard line. He did what appeared to be a stutter step to avoid the defender and went immediately to the sideline after a 2-yard gain.

McCaffrey stayed in the sideline medical tent for 22 minutes before emerging and heading to the locker room. He walked under his own power with a slight limp.

McCaffrey was replaced by Chuba Hubbard, a 2021 fourth-round pick out of Oklahoma State.

McCaffrey, who in 2019 became the third player in NFL history to have 1,000 yards rushing and receiving in the same season, entered the game as the NFL's leader in yards from scrimmage with 324 yards.

McCaffrey missed 13 games last season with multiple injuries, including a high ankle sprain suffered in Week 2. He returned this season looking stronger than ever.

He left late in the third quarter of last week's win against the New Orleans Saints to get a couple of IV bags for what he called "onset cramps.'' He said earlier this week he was good go to.

On Thursday night, Carolina's offense struggled after McCaffrey's departure and went into halftime with only a 7-6 lead. Quarterback Sam Darnold, who completed 9 of 13 pass attempts for 121 yards with no sacks before McCaffrey's injury, finished the half 4-of-7 for 37 yards with three sacks.

McCaffrey's value as a blocker often gets overlooked. In the Panthers' opener, he saved Darnold from a sack by picking up the New York Jets' tackle running free. The block allowed Darnold time to step up and to his left to throw a 57-yard touchdown pass to Robby Anderson.

"That play doesn't happen [without McCaffrey],'' coach Matt Rhule said after the 19-14 victory.

Tight end Dan Arnold said McCaffrey helps open up all the possibilities of offensive coordinator Joe Brady's offense.

"We kind of stopped as a tight end group [in film review] and said, 'This is the kind of player he is,'" Arnold said after seeing the replay of McCaffrey's block. "It's exciting to be able to play with a guy like that, that will step in front of it no matter what. He wants to win, not only for himself, but everybody else.

"On the flip side, that's what he demands from everybody else."