One of the hidden reasons the Giants' big three defensive ends were so productive last season was the unheralded play of the fourth. Dave Tollefson, rarely in the headlines, gave the Giants flexibility and the occasional breather during games, allowing them to use a stronger rotation of players to attack quarterbacks.

Even the Three Musketeers were really a group of four after all.

The Giants never replaced Tollefson in their rotation this year. It's been mostly Jason Pierre-Paul, Justin Tuck and Osi Umenyiora. But they might have found a perfect way to fill that void with a player who has been on their roster since 2006: Mathias Kiwanuka.

Drafted as a defensive end and moved to linebacker early in his career, Kiwanuka played every snap Sunday as a lineman. He wound up with two sacks, helping the group snap out of its long funk.

Is Kiwi the new Tollie?

"You can look at it that way," defensive coordinator Perry Fewell said Friday.

Two developments have allowed the Giants to flex Kiwanuka back to the line, a position he might find himself at again Monday night against the Redskins -- particularly if Pierre-Paul is at all limited by the back injury that kept him out of practice Friday.

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The first is the health and development of the linebackers, particularly Keith Rivers, who is not on the injury report this week, and second-year players Mark Herzlich and Spencer Paysinger. The second is the return of Kenny Phillips, allowing the Giants to employ their three-safety look. Three safeties means two linebackers, and that means Kiwanuka is free to be on the line.

That's where he wants to be, anyway. "I definitely love being down there," Kiwanuka said this week. "That's what I do naturally. As a football player, that's what I'm most used to. Whenever we can get that rotation, it kind of keeps everybody fresh and keeps that enthusiasm getting after the quarterback."

The Giants say the move was game plan-specific, just as it was against the 49ers, the other game in which Kiwanuka played mostly on the line. That those two games accounted for 11 of the team's 30 sacks this season might prompt the Giants to do it more often.

Kiwanuka also adds an element of deception when he's on the line.

"Sometimes you don't know if the offense counts him as a linebacker or defensive end, so when he drops his hand down, they don't know if he's going to drop off or rush," Fewell said. "I think it's a little bit of guessing on their part on what he's going to do."

It leaves Kiwanuka guessing from week to week, too, depending on how the coaches plan to use him against particular opponents.

Said Kiwanuka, "We know pretty early on in the week how it's going to go."