EAST RUTHERFORD, N.J. -- A full week into training camp, all three Giants starting linebacker jobs remain open.

Mark Herzlich, Spencer Paysinger and Keith Rivers are the first unit, according to the first unofficial depth chart of the summer, released by the team on Thursday. But that is far from set in stone one week before the team's first preseason game, in Pittsburgh next Saturday.

"There's competitions all along the board, really," linebackers coach Jim Herrmann said prior to Saturday's practice. "And to me, that's really good. Because if they're all getting better, we're gonna be better."

"Playing linebacker's not easy," Herrmann continued, "and there are injuries that happen, and the next guy that steps in is just as talented as the guy that had to take a week off."

Chase Blackburn and Michael Boley, starters for the majority of last season, are gone. Herzlich and Paysinger, both undrafted, are entering their third seasons, but have just seven NFL starts between them.

Rivers, a former No. 9 overall draft pick, started six games for the Giants last season but has been injury prone in his four-year NFL career.

There are some intriguing prospects on the second unit. Jacquian Williams has shown flashes of great potential in his first two seasons, but is working his way back from a knee injury. Dan Connor started eight games for the Cowboys last year. And Aaron Curry is a former No. 4 overall pick trying to resurrect his career.

The third-stringers are Kyle Bosworth, Jake Muasau and rookie Etienne Sabino.

"It's been great competition, and the guys, the group, the room, they're all good guys," Hermann said. "There's nine good men there, and they all understand they're competing, but they're also trying to help each other get better. As a coach I can't ask anything more from them."

As for practice on Saturday, Herzlich made the biggest play of the day for the linebackers. During a two-minute drill at the end of practice, Herzlich dived for a deflected pass from rookie quarterback Ryan Nassib, hauling it in for an interception. That can only help him in his quest to secure the starting middle linebacker job.

That said, Hermann indicated Saturday that the Giants could have two different starting linebacker units -- one for first and second downs, and another one for third downs.

"To me the ballgame's broken up into two phases," Herrmann said. "First and second down, and then to me third down is a completely different game, because the majority of the teams in this league are gonna throw the ball every play on third down. And so your mind-set's different, the guys you put on the field are different."

He has some inexperienced players vying to play important spots, but Herrmann sounds excited about what he's working with.

"We have a lot of guys who fit into different little roles," Herrmann said, "which is exciting for them, because they may not be a starter on first and second down, but come third down they can be a starter because of their talents."