PITTSBURGH — Pittsburgh Steelers outside linebacker T.J. Watt has been released from the hospital and is back home recovering after a surgery to repair a partially collapsed lung, head coach Mike Tomlin said on Friday.

Tomlin then ruled Watt out for Monday’s game against the Miami Dolphins and it is unclear just how long Watt will miss this season. Tomlin says he is unsure on the recovery time for Watt at this juncture.

Watt underwent a treatment known as ‘dry needling’ in the facility on Wednesday, which is a physical therapy technique that aims at muscle knots and alleviating pain.

It is a general treatment that many players undergo each week without repercussions. However, Watt’s caused him great discomfort throughout Wednesday, and they sent him to the hospital which revealed the partially collapsed lung, balding to surgery.

With Watt out, the Steelers will have Alex Highsmith and Nick Herbig as their starters against the Dolphins. Both of those players have started at different points this year, but they have not played a game without Watt in the lineup.

Highsmith, Watt’s best friend on the team, said he has been in contact with the star pass rusher, and he remains in good spirits.

“It’s definitely a scary situation, tough situation. I’ve just been praying for him. I know he’s getting better,” Highsmith said.

This is the second Steelers player who has gone to the hospital for a check this week. DK Metcalf did so in Baltimore on Sunday night following the team’s win over the Ravens, after experiencing stomach pain. He is expected to be limited this week, but should play on Monday against the Dolphins.