JuJu Smith-Schuster had a crucial fumble against the Saints. Chris Graythen/Getty Images

After a crucial fourth-quarter fumble in a 31-28 loss to the New Orleans Saints on Sunday, Pittsburgh Steelers wide receiver JuJu Smith-Schuster took full responsibility for his mistake.

Smith-Schuster on Monday posted on Twitter: "When I’m at my lowest, I’m not going to hide. I’m sorry. That loss was on me. I let everyone down, it won’t happen again."

Pittsburgh was almost within field-goal range with 37 seconds remaining when Smith-Schuster fumbled at New Orleans' 36 yard line. The ball left the 22-year-old's grasp after he was tackled by Saints' defensive tackle Sheldon Rankins and cornerback P.J. Williams. Because Smith-Schuster never had a knee or arm touch the turf, the officials ruled it a fumble in what was the last meaningful play of the game.

"It's tough to go out like that," Smith-Schuster told reporters after the game. "I got tackled. I fumbled. Game over. I was just trying to get down. They made a good play."

It was an otherwise strong game for the second-year receiver. Smith-Schuster finished with 11 receptions for 115 yards.

Teammates and other NFL players rushed to Smith-Schuster's defense after the game. Steelers wide receiver Antonio Brown said Smith-Schuster is "a reason we're here."

Steelers quarterback Ben Roethlisberger on Monday told a radio show that he hated that the fumble happened to Smith-Schuster and described him as a "special talent" and a "special player."

Nevertheless, the loss puts the Steelers' playoff hopes in jeopardy entering Week 17.

To win the AFC North, Pittsburgh needs to beat the Cincinnati Bengals and for the Cleveland Browns to win a road game against the Baltimore Ravens. The Steelers could also earn a wild-card berth if they beat the Bengals, while the Tennessee Titans and Indianapolis Colts tie.