Defenses in fantasy football are a fickle beast to figure out. Touchdowns can sway the course of a defense's fantasy season, but are nearly impossible to predict. This is why many fantasy players are fans of a strategy called "streaming defenses." If you've been playing for years, this is nothing new to you, but for those unaware, what this entails is using a waiver claim most weeks to acquire a defense with an enticing matchup. This doesn't always work, but for many players it's a better option than rolling the dice with an average defense week after week.
So with this in mind, here are some lesser-owned defenses to target for Week 13.
Minnesota Vikings D/ST (5.9 percent owned) at Carolina Panthers
If you're streaming defenses and the Vikings are available, look past their one-point outing last week. That was against Aaron Rodgers and the Packers. And despite that small fantasy showing, their defense actually played quite well, holding the high-octane Packers offense to just 24 points.
Minnesota's pass-rush was stymied against Rodgers' quick release, but up next on the schedule is a date with Cam Newton and the five turnstiles lined up in front of him. Newton had taken 21 sacks in his last five games prior to his bye week, while the Vikings had recorded 20 sacks in their five games prior to last week. The Vikings' pass-rush could create a few turnovers and put Newton on his heels early in this game.
Indianapolis Colts D/ST (22.5 percent owned) vs. Washington Redskins
Washington has allowed 11, 22 and seven fantasy points to opposing defenses in their last three games, and I'd expect Colts head coach Chuck Pagano to dial up some blitzes to keep Robert Griffin III unsettled in this game. If the Colts can force RGIII into some errant throws and runs, they could turn in a solid fantasy performance.
St. Louis Rams D/ST (55.7 percent owned) vs. Oakland Raiders
After struggling at the start of the season, this Rams defense has been a lot of fun to watch recently. They've scored double digit fantasy points in three of their last four games, including games against Peyton Manning and Philip Rivers.
As far as rookie quarterbacks go, Derek Carr of the Raiders has been pretty solid, only taking 12 sacks and committing 11 turnovers on the season. However, the Raiders offense is still lacking serious playmakers, and with the Rams defense stiffening up, it could be a long afternoon for Carr and the Raiders leading to a nice fantasy outing for the Rams.
Miami Dolphins D/ST (40.1 percent owned) at New York Jets
Like with the Vikings, disregard Miami's fantasy performance from Week 12. That was against Peyton Manning at home, and he was coming off an embarassing loss to the Rams. There was no way he wasn't going to light them up. Next up on the slate for the Dolphins is a solid matchup with the Jets on Monday Night Football.
The Jets have been a little less fantasy friendly with Michael Vick under center, but they still represent a nice target to stream against. Miami has forced 12 turnovers in their last six games, and the Jets as a whole aren't the best team at protecting the ball. If the Dolphins are on your waiver wire this week, they're worth rolling out against the Jets.
Good matchups: DET vs. CHI (Thurs.), HOU vs. TEN, ARI at ATL
Matchups to avoid: NE at GB, NO at PIT, PHI at DAL (Thurs.)
Frisky and risky streaming plays:
New York Giants D/ST (3.2 percent owned) at Jacksonville Jaguars -- Yes, the Jaguars are a great streaming target, as Blake Bortles has taken 14 sacks and committed six turnovers over his last four games, but the Giants haven't registered a double-digit fantasy performance since Week 4. I also worry that the Jags could control the clock with Toby Gerhart and Denard Robinson, lowering the Giants' chances for much needed turnovers. That's why it's a frisky play instead of a straight recommendation.
Baltimore Ravens D/ST (37.2 percent owned) vs. San Diego Chargers -- The Ravens defense isn't the same dominant unit it once was, but the Chargers have not been playing great football lately either. At home, this could be a game where the Ravens deliver on defense against a beat up Philip Rivers and company.
-- Alex Gelhar is a fantasy and features writer for NFL.com. Follow him on Twitter @AlexGelhar.