Sometimes the game is cruel.

Ryan Connelly, a rookie linebacker, not only earned a starting job with the Giants, but he was making plays to help his team win games. He will not be doing that any longer, as Connelly went down early in the fourth quarter of Sunday’s 24-3 victory over the Redskins with a serious knee injury.

Connelly twisted awkwardly making a tackle on Redskins quarterback Dwayne Haskins and never got to his feet, as the cart came out to take him to the locker room. He was on crutches after the game. It has all the makings of a torn anterior cruciate ligament. Connelly will have an MRI exam Monday.

“It does not feel good,’’ Connelly said. “I’m hoping it’s nothing is what I can say.’’

Before he was hurt, Connelly was showing why he was elevated into a starting role in Week 2. He came up with his second interception in as many games when he picked off Case Keenum, securing a deflection off cornerback Janoris Jenkins. Connelly also got his first NFL sack. He became the first Giants linebacker with a sack and interception in the same game since Dec. 23, 2007, when Kawika Mitchell did it in Buffalo.

Losing him is a problem, as the Giants are painfully thin at inside linebacker. They started Connelly and newcomer David Mayo on Sunday, as Alec Ogletree is out with a strained hamstring.

Rookie RB Jon Hilliman, signed this past week off the practice squad, made his NFL debut and actually was the lead back on a third-quarter series. Hilliman (10-33) carried the ball six times on a drive that made it to the Redskins 2-yard line. It was one carry too many for Hilliman, who lost the ball on a fumble.

The Giants were not concerned rookie QB Daniel Jones would fall into a rut after throwing two interceptions.

Asked if Jones is a fast learner, coach Pat Shurmur said, “Daniel? He’s smarter than all of us. He’s way smarter than me.’’

Ereck Flowers, the Giants’ first-round pick in 2015, started at left guard for the Redskins and was hit with one penalty — hands to the face — that was declined by the Giants. … LB Lorenzo Carter was forced out in the second half with a neck injury.

WR Golden Tate will rejoin the Giants on Monday after serving his four-game suspension for violating the NFL’s policy on performance-enhancing substances.

“I can’t wait for him to get back,’’ tight end Evan Engram said. “I know he’s itching to get back on the field with us. It will be good to have his presence back in the locker room and on the field. We got to do our best as an offense to get him caught up to speed on everything so he can be ready Sunday.’’

The Redskins were depleted before the game even started. Two of their best players were listed as questionable but were activated because of injuries. Rookie WR Terry McLaurin (hamstring) and G Brandon Scherff (ankle) were both sidelined, weakening the Washington offense. … For the second consecutive week, Eli Manning did not go out for the coin toss with the other team captains.