FOXBOROUGH — A circle has no end.
A book has one end.
A line has two ends -- unless, that is, it's the New York Giants' defensive line, which has four ends, each of whom has the ability to take down Tom Brady.
In something of a nose-thumbing to football tradition, not to mention the laws of physics, the Giants have built their defense around four pass-rushing defensive ends that sometimes might be on the field all at the same time.
The Giants tied for third in the NFL with 48 sacks last season, led by the prolific Jason Pierre-Paul and his 16.5 takedowns of opposing quarterbacks.
In three postseason games, Osi Umenyiora has a team-best 3.5 sacks and a forced fumble. A change from a linebacker-focused 3-4 defense to a defensive line-focused 4-3 defense has allowed Pierre-Paul, Umenyiora and their cohorts to attack the backfield relentlessly off the edge.
Suffice to say, the means by which the Giants beat Brady and the Patriots four years ago could well be the means by which they may beat Brady and the Patriots a week from Sunday in the Super Bowl in Indianapolis.
"They can rush the passer; there's no doubt about that," said Brady, who was sacked twice and fumbled when the Patriots and Giants met at Gillette Stadium in early November.
"From playing them before, you understand that. They strip-sacked us on our own 10-yard line when we played them last. They get a lot of turnovers. They put a lot of pressure on you with their front four. They have a big, physical group that plays really well together."
In the NFC title game against San Francisco, the Giants sacked 49ers quarterback Alex Smith three times and hurried him six other times.
In an upset of Green Bay the week before that, the Giants sacked Packers quarterback Aaron Rodgers four times and hurried him five times.
Most memorably of all, four years ago in the Super Bowl, the Giants sacked Brady five times and hurried him nine times. Justin Tuck strip-sacked Brady in the final seconds of the first half to thwart what could have been a scoring drive.
The dominance of the Giants' defensive line in that game was what, more than anything else, did in the Patriots.
"That's where our energy comes from, that's where our confidence comes from, that's where our swagger comes from," Giants defensive coordinator Perry Fewell told reporters before the NFC title game last week. "Those guys, unlike most teams that you are associated with, they set the tone for us. They are the catalysts for what we do and how we do it."
Most of the time, the Giants rotate their defensive ends into and out of the game, playing them two at a time alongside interior defensive linemen Linval Joseph and Chris Canty. In some passing situations, however, they might play three or even four defensive ends at one time to put more pressure on the quarterback.
To get more ends into the game, one of the defensive ends might move inside and line up as a defensive tackle -- but still have the athleticism to get to the quarterback like he would from the outside.
"It's not their steady defense, but sometimes they do it out of an odd front where they have (Mathias) Kiawanuka kind of floating behind the line scrimmage as a fourth rusher, but you don't know exactly where he's going to come," Patriots coach Bill Belichick said.
"Teams that have defensive ends that can move them inside, they move them inside and put another defensive end out there. We've seen plenty of that during the course of the year. Those four or five guys, six guys, they have a bunch of them, and they roll them all in there. They're all good and some of them have their own unique skills to rush the passer and that makes it a different matchup when one guy is in there relative to another guy."