It’s every team’s biggest preseason fear.

A player limps to the sideline or gets carted off the field after an injury. So when CB Justin Miller, who appeared in only two regular-season games last year, hobbled to the sideline in the second quarter Saturday night, the Jets definitely crossed their fingers.

Miller hurt his left foot, but unlike Giants DE Osi Umenyiora, he escaped serious injury. When Jets head coach Eric Mangini was asked at today's new conference about Miller’s chances of playing within the next two weeks, he delivered a little comic relief.

“I haven't gotten a line out of Vegas, but I'd say pretty good,” he said.

That was good news, but the Jets are not devoid of depth or versatility in their defensive backfield.

Three players — Dwight Lowery, a fourth-round pick who intercepted 13 passes in 25 games at San Jose State; David Barrett, a veteran with 75 NFL starts on his résumé, and Hank Poteat, a heady performer — have taken first-team reps at various points throughout the summer.

“That's part of the thought process, to have multiple guys that can fill in,” Mangini said. “You saw last week we worked a lot of guys in a lot of different spots in the secondary to build that flexibility.”

On the Giants’ second possession, the Jets juggled their backfield. Star safety Kerry Rhodes began the drive on the sideline while Barrett played safety for the first time as a pro. DB had practiced the position but was surprised to find out before the game that he’d be getting reps there.

“I was kind of shocked, but I knew most of the stuff,” he said. “It was just a matter of going out there, seeing it and knowing what to do.”

Barrett says he’s going to do whatever he can to help the Jets win. And if that means moving to safety occasional, then so be it.

“It felt a little different but good,” he said. “Being in the back end is a little different from being on the corner on the island the whole time, so you have to get used to it.”

In addition to Barrett’s insertion, Lowery entered the game at the same time. He took Miller’s right corner post for a few plays in the first quarter prior to Miller’s injury in the second quarter.

The 5’11”, 201-pound corner had another effective night, finishing with a team-high five tackles (four solos, one assist).

“I think I played good. There are always things you can improve on, but overall I feel like I played really well,” Lowery said. “All you have to do is look at the tape and improve on the things you need to improve on so you can keep setting the bar high.”

Lowery could be the latest in an impressive list of Green & White players who’ve gone from the fourth round to key contributors. WR Jerricho Cotchery (2004), S Kerry Rhodes (’05) and RB/KR Leon Washington (’06) all preceded Lowery to the pros and have given the Jets fans plenty of reasons to smile.

It’s too early yet to make a prediction on Lowery, but he seems to have the goods. He’s not only a ballhawk but a cool customer who’s not been overwhelmed a bit by the NFL. According to pressbox stats, he has totaled 18 tackles (15 solo), four PDs and one interception in three summer games.

“I look at it as it’s a situation for me just coming in and competing. It’s really not up to me whether I’m a starter or I’m a backup,” he said. “The only thing I can control is what I do day in and day out.”

And Lowery, who expresses his thoughts in an un-rookie-like manner, says he’s found comfort in the Jets defense.

“I think that comes from understanding what the other guys are supposed to do, too, and understanding where you fit into the defense and what we are trying to execute and what we are trying to get done with the defenses that are getting called,” said the 22-year-old. “You get to a certain point where you feel like you can anticipate what our coach is going to call.”

Prior to today's practice, Miller met with reporters for a quick talk. Always one for fun clothing, he sported a T-shirt with Rolling Stones lead singer Mick Jagger the subject.

“I still have great spirits,” he said when asked if he was down about his recent injury. “I’m always smiling.”

Mangini, the Patriots' secondary coach from 2000-04, continues to preach the importance of versatility in his D-backfield.

“If the corners know safety and the safeties know corner, and it's more of a run-down situation but you want to play sub people, you can put a bigger body down and put a smaller body back. You can blitz from a lot of different looks,” he said. “Every time you're down, it doesn't just mean one thing. You can show down and play something totally different. That's really what I'm striving for in the secondary.”