The Washington Redskins expect their defense to carry the team while the offense weathers injuries along the offensive line and endures the growing pains associated with a rookie quarterback.

But on Saturday night, the starting defense had a rough outing in a 33-31 loss at Soldier Field, losing two starters and putting up little resistance against the Chicago Bears’ passing attack.

Starting outside linebacker Brian Orakpo, one of the team’s best defensive players, and strong safety Brandon Meriweather were knocked out of the game within two minutes of one another during the first quarter. And the secondary gave up big gains to Chicago’s starters and backups in a first half that ended with Chicago up, 20-10. Orakpo and Meriweather are scheduled to undergo MRI exams Sunday. Neither knew the extent of his injuries.

Robert Griffin III and the offense struggled against the Bears a week after Griffin’s impressive preseason debut.

Griffin found himself under duress much of the night. He was sacked three times and fumbled once. He completed 5 of 8 passes for 49 yards, and his three sacks counted for a total loss of 19 yards. His quarterback rating was 79.7.

The offensive line featured left tackle Trent Williams and left guard Maurice Hurt, who had missed portions of this week’s practices with foot and knee injuries, respectively. But the line was without right guard Chris Chester for a second straight game, because of a sprained ankle.

Orakpo injured his left shoulder with 3 minutes 50 seconds left in the first quarter and never returned. The fourth-year pro tried to tackle Bears wideout Devin Hester after Hester made a catch in the flat. But as Orakpo stretched out his left arm to grab Hester, the receiver spun off him, stretching Orakpo’s arm backward, and turned upfield.

Orakpo fell to the ground, grabbing his left arm. He was tended to by trainers before he was helped off the field and taken to the trainers’ table behind Washington’s bench. Orakpo’s shoulder pads were removed and his shoulder was wrapped. He did not return.

It’s the same side on which Orakpo tore a pectoral muscle in the 2011 season finale. He had surgery during the offseason to repair the tear and hadn’t been hampered by it this preseason.

Orakpo said that his shoulder already was feeling better. The linebacker said he believed the injury was related to scar tissue in the shoulder and pectoral muscle area from the 2011 injury.

“I don’t think it’s nothing too serious, but we just have to play it by ear. We’ll get an MRI in the morning, and then we’ll know,” Orakpo said. “You get those type of injuries, little hyper-extension when you try to arm-tackle. You get an uncomfortable type of feeling. . . . But I really don’t know anything right now. My strength is good right now, so I don’t think it’ll be a long process.”

Two minutes after Orakpo was hurt, Meriweather went down with an injury to his left knee. Two plays after Griffin was sacked and fumbled the ball at the Washington 8-yard line, Meriweather was injured on a touchdown run by Chicago’s Michael Bush.

It appeared that an offensive lineman fell on Meriweather’s knee. Medical staff worked on him for several minutes before the safety hobbled off the field and was taken to the trainers table behind Washington’s bench.

Meriweather — who was making his return to Chicago, where he played last season — walked back and forth gingerly behind the bench while he was examined further, and then was taken to the locker room.

Washington’s defensive struggles began before the injuries, however. The Redskins took possession to start the game but were forced to punt after six plays.

Chicago quarterback Jay Cutler, who didn’t play in his team’s preseason opener, wasted little time, connecting with Brandon Marshall on a 41-yard pass on the Bears’ first offensive play.

Marshall had a healthy cushion on cornerback Cedric Griffin, who is competing to be the third corner in Washington’s defense. Three plays later, Cutler went back to Marshall again, this time taking advantage of a mismatch in a formation that had cornerback DeAngelo Hall lined up as a safety, and Meriweather lined up opposite Marshall. Marshall gained 20 yards on that reception.

Cutler picked on Cedric Griffin again, connecting with rookie Alshon Jeffrey for a 16-yard pass to the Washington 1. Bush scored from one yard out for his first touchdown of the night.

Orakpo was injured on the next possession, which ended in a Chicago punt. But Washington gave the ball right back when Robert Griffin III tried to throw the ball away as defensive end Israel Idonije hit him. Julius Peppers recovered the fumble, and Bush scored two plays later, giving Chicago a 14-0 first-quarter lead.