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By Greg Ambrosius, National Fantasy Football Championship, Special to SI.com

Most fantasy football leagues use defensive/special teams scoring these days, with points being accumulated for everything from fumbles and interceptions to shutouts and sacks. Most fantasy-league owners wait until the final rounds to pick a defense, but lately top teams such as Minnesota, Chicago and San Diego have earned the right to be picked within the top 125 picks.

Here's a look at the top 25 fantasy defenses to grab in 2008:

1. San Diego

The Chargers ranked fifth in points allowed per game last year, allowing just 17.8, but they added even more fantasy punch with 5 defensive TDs, 2 special teams TDs, 55 forced turnovers and 42 sacks. Shawne Merriman led the way with 12.5 sacks, while Antonio Cromartie had 10 interceptions and one TD. This defense has everything, so grab it if you can.

2. Minnesota

The addition of DE Jared Allen makes this defense as good as any other in the NFL. The Vikings finished with eight defensive TDs last year, 38 sacks, 42 forced turnovers and one special teams TD. LB Chad Greenway led the way with 105 tackles and Darren Sharper led the team with four interceptions and one TD. This is a good defense that just got better this off-season.

3. New England

While the offense got all the press last year, this defense wasn't too shabby, either. It ranked fourth in points allowed per game (17.1) and had 6 defensive TDs and 2 special teams TDs. Yes, it lost CB Asante Samuel to free agency, but LBs Tedy Bruschi, Mike Vrabel and Adalius Thomas lead a solid linebacking corp. More turnovers will come this year, so grab this D now.

4. Dallas

The addition of Pacman Jones has this defense rising in off-season mock drafts. There's no guarantee that Jones will be eligible for the full season, but even without him the Cowboys forced 45 turnovers last year, scored three defensive TDs and had 46 sacks. CBs Anthony Henry and Terrence Newman lead an aggressive secondary that will be even better with Pacman on the prowl.

5. Green Bay

The Packers have quickly become one of the most improved defenses under coach Mike McCarthy as last year it forced 41 turnovers, scored four defensive TDs and added 36 sacks. LBs Nick Barnett (135 tackles) and A.J. Hawk (105 tackles), lead the way, with CBs Rod Woodson (4 INTs) and Al Harris (2 INTs) leading the secondary. Look for even more blitzes and better numbers in '08 from this defense.

6. Chicago

The Bears ranked 28th in total defense last season, but the special teams with Devin Hester makes this a team to get on draft day. Hester scored six special teams TDs last year -- two on kickoffs and four on punts -- and the defense added one more TD, 49 turnovers and 41 sacks. Because of Hester, this is a "defense" worth drafting this year.

7. New York Giants

This defense carried the Giants to last year's Super Bowl title as it was dominant down the stretch. The Giants finished last year with 53 sacks, five TDs and 37 forced turnovers. Defensive ends Osi Umenyiora (13 sacks) and Justin Tuck (10 sacks) lead the way, while Ahmad Bradshaw leads an improved special teams unit.

8. Jacksonville

The Jags are steady yet unspectacular on defense, which earns them a Top 10 fantasy ranking. They ranked 10th in points allowed last year at 19.0, while ranking 12th in total defense. They scored 3 defensive TDs, one special teams TD, and had 33 forced turnovers and 37 sacks. Maurice Jones-Drew and Dennis Northcutt lead special teams units that are as good as they come.

9. Pittsburgh

The Steelers finished second in points allowed last year at 16.8 and finished with 2 defensive TDs, 1 special teams TD, 36 forced turnovers and 36 sacks. S Troy Polamalu remains one of the game's top safeties, but he needs to stay healthy for this defense to click on all cylinders. It's also time for an upgrade on the special teams units.

10. Seattle

The Seahawks finished sixth in points allowed per game last year at 18.2 and they were among the most aggressive defenses in the league. They finished with two defensive TDs, three special teams TDs, 43 forced turnovers and 45 sacks. DE Patrick Kearney (14.5 sacks) and LB Julian Peterson (9.5 sacks) lead a defensive team that is still young and getting better with each game.