NEW YORK (CBSNewYork) — You can’t make it up.

The Jets‘ unfathomable run of injuries got even worse on Tuesday as head coach Adam Gase announced backup-turned-starting quarterback Trevor Siemian will miss the rest of the season due to a left ankle injury suffered during the 23-3 loss to visiting Cleveland on Monday night.

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Gase said an MRI revealed ligament damage that will require surgery.

“We’re still going through the procedures as far as surgery options,” Gase said. “So, obviously, we’ll have to address our quarterback position from here on out.”

Siemian suffered the injury in the second quarter when he threw a long incomplete pass to Ryan Griffin and the Browns’ Myles Garrett slammed into him and fell on top of him — and was penalized for roughing the passer. Siemian, who somehow walked off the field after the play, was on crutches and in a walking boot after the game.

“I think all of us were surprised that when you watch it, it wasn’t a break, like probably what a lot of us have seen in the past,” Gase said. “I mean, it’s an ugly looking play. I think there’s a good amount of damage to where surgery will be needed and it’s going to be time for him to recover.”

A four-year veteran, Siemian was installed as the starter after Sam Darnold was diagnosed with mononucleosis early last week. Darnold, the No. 3 overall selection in last year’s draft, could miss anywhere from three to seven weeks, according to reports. However, Gase said Darnold was at the team’s facility Tuesday after resting at home all last week.

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“He’s feeling better, but really it’s the doctors letting us know when to proceed with him,” Gase said.

Luke Falk, who was elevated from the practice squad to the active roster prior to Monday night’s game, made his NFL debut following Siemian’s injury and played fairly well, completing 20 of 25 passes for 198 yards and didn’t commit a turnover. The Jets are expected to sign at least one quarterback in the next day or so to back up Falk.

Falk was a sixth-round draft pick last year by Tennessee out of Washington State. He was among the Titans’ final cuts and claimed by Miami, where Gase was then the coach. Falk was waived by the Dolphins in May and claimed by Gase and the Jets. He was among the Jets’ final cuts, but added to the practice squad after beating out Davis Webb in the preseason.

The Jets’ injury woes started during the preseason when they lost stud linebacker Avery Williamson for the season due to a knee injury. The situation got dire when star linebacker C.J. Mosley and rookie defensive lineman Quinnen Williams were knocked out of the season opener, a 17-16 loss to visiting Buffalo, with groin and ankle injuries, respectively. Also hobbled in that game was starting wide receiver Quincy Enunwa, who was later ruled out for the season with a neck injury.

Not long after that, Darnold’s diagnosis stunned everyone.

In addition to Siemian’s injury, veteran Demaryius Thomas, acquired from New England to soften the blow of losing Enunwa, was forced out of Monday night’s game due to a reaggravation of hamstring injury.

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Already 0-2 and in danger of having their season spiral out of control, the Jets’ schedule only gets more difficult. New York plays at Super Bowl champion New England this Sunday, then has its bye, before playing the two best teams in the NFC East, at Philadelphia and home against Dallas,. The Jets then take on the Patriots again, on Oct. 21 in prime time at MetLife Stadium.