Henry Hynoski is not a marquee name, but he fills a valuable role within the offense and the Giants are hoping their third-year fullback did not sustain a serious injury.

It didn’t take long yesterday — the second play of the first-team period of the first organized team activity practice — for the Giants to see one of their players down on the field. Hynoski knocked knees with running back Andre Brown on a running play and Hynoski had to be carted off the field holding his left knee.

“I didn’t see it,” Eli Manning said. “I handed the ball off and just saw him on the ground after. I don’t know exactly what happened. I haven’t seen the film yet. I don’t know how severe the injury is, so hopefully it’s not too bad, and he can be back either for the spring or at least for training camp.’’

Hynoski, a valuable blocker, was sent for an MRI exam.

“I said a few prayers,’’ coach Tom Coughlin said, “and I’ll continue until I hear what it is.”

* The coaching staff would love to see third-year WR Jerrel Jernigan emerge as the punt returner, but ball security has been an issue.

Jernigan said he has completely revamped his approach and special teams coordinator Tom Quinn has been “harping on me about the way I’ve been catching, he finally convinced me to change my techniques back there.’’

Jernigan was fielding punts like a receiver.

“Breaking old habits I had before,’’ he said. “Basically I was catching with my hands, kind of like catching a pass. Now I’m catching it with my body and letting my hands come together.’’

* Terrell Thomas, attempting to come back from a third ACL surgery to his right knee, is not going to do much or anything in these OTAs.

“There’s really no plan right now other than when I’m ready I’m ready,’’ Thomas said. “But the knee’s doing great.’’

The latest procedure was different than the first two in that his own patellar tendon was used in the repair rather than a cadaver, making for a longer recovery this time around.