Knee gives out on Nunez - again.

HOUSTON – It’s been about sore knees, but it’s beginning to sound more like a broken record.

Back in August, Dustin Pedroia returned from a DL stint for a knee injury, played one game… and soon returned to the DL again.

Two weeks ago, after missing nearly two weeks with a sprained PCL in his right knee, Eduardo Nunez  had two at-bats…and was sidelined again after aggravating the same knee when he caught a spike in the dirt near home plate.

On Thursday, Nunez swung at the second pitch he was in the first inning, broke out of the box, limped badly and soon collapsed on the field before reaching first base. Nunez said he felt some discomfort with his first swing, then felt pain with the first step he took out of the box.

It was bad enough that Nunez had to be carried off the field by manager John Farrell and a member of the training staff. Several hours after the game, Major League Baseball announced that it had approved the Red Sox' request to remove Nunez from the playoff roster, replaced by Chris Young.

“We have to go through a protocol here to determine his activity before we make a roster move,’’ said Farrell after the Red Sox aborbed an 8-2 drubbing from the Houston Astros in Game 1 of the ALDS. “But I think it’s pretty safe to say, given how he went down today, he would not be available.’’

Teams are allowed to make substitutions for injured player players during a series, but such a move also makes the player unavailable for the next series.

“It’s not ready yet,’’ acknowledged Nunez after the game when asked about the knee. “We did everything we can. We didn’t expect that. We did a lot of tests, a simulated game…we did everything we can to be ready. And we obviously know my knee’s not ready yet.

“We tried to rush twice because we didn’t have a lot of time. We tried to rush a little bit. I thought I was a little more ready than I am. (You can’t replicate) the intensity of a playoff game. You test, you do a simulated game but you think about what you’re doing beforehand. In the game, obviously, it’s more intense, it’s more about reacting and you don’t have as much control of yourself.’’

The Sox will wait until Friday morning before making any transaction official, but Nunez said he expected “to be out for the series. We’ll see how I am for the next series or the World Series.’’

He’ll undergo an MRI back in Boston, but the belief is that there’s no further damage to the knee.

“There’s no swelling,’’ he said. “There’s just the same pain there was before, a little more painful this time. We’ll see what the MRI says in a few days.’’

Nunez is extremely popular with his teammates, and some were rocked by the sight of him crumpled on the turf, short of first.

“I was watching (Alex Bregman) field the ball,’’ said Xander Bogaerts. “Then I looked over and the way he went down, I could see how much pain he was in. You’ve got to regain your focus back the game, but that’s obviously a big blow right there. First at-bat, similar to the last time, but this time he went down and couldn’t get back up.’’

With Nunez almost certain to be removed from the roster, Young will take his spot and could well find himself in the lineup Friday against Houston lefty Dallas Keuchel.  The Sox have already said that Hanley Ramirez will play first, leaving the DH slot open for a righty bat like Young’s.