The St. Louis Rams are above .500 for the first time in six seasons. If they want to stay there, the defense might have to do the heavy lifting again.

St. Louis goes for its first three-game winning streak since December 2006 on Sunday against the Miami Dolphins, who are trying to win their fifth straight at home in this series.

The Rams (3-2) had little to celebrate in the previous five years with 15 victories during that span, but they've bested their win total from last season by one. The improved play has come under new coach Jeff Fisher, who was courted for the Miami job before being hired by St. Louis in January.

With a 17-3 victory over previously undefeated Arizona on Oct. 4, the Rams are above the break-even point for the first time since they were 4-3 in '06.

"I've never been there before," fifth-year defensive end Chris Long said. "I'm unfamiliar with the sound of it, but I'm liking it."

The Rams' strong play in the last two games has been due in large part to their defense, as they've allowed 16 points in that span. End Robert Quinn had three of the club's season-best nine sacks against the Cardinals and St. Louis gave up 45 rushing yards.

"Those guys played outstanding," said Sam Bradford, whose 141 passing yards were the second fewest of his career. "They've played great all year and they have kept us in a lot of games."

That's been critical as Bradford has struggled to lead an offense that's ranked 29th in the league with 278.0 yards per game. The Rams would be even worse offensively if not for rookie Greg Zuerlein, who's gone 13 for 13 on field goals and made four of at least 50 yards.

Bradford, who has a 78.6 rating, may have to look more to receiver Brandon Gibson and tight end Lance Kendricks on Sunday after leading receiver Danny Amendola suffered a clavicle injury against Arizona. Amendola, who has 32 catches for 395 yards and two touchdowns, could be out for several weeks.

"Obviously, losing Danny is big," Bradford said. "Everyone knows that he's a big part of our offense. A lot of what we do runs through him."

The Rams' offense could get a boost if Steven Jackson can build on his season-best 76-yard rushing performance versus Arizona, but the Dolphins' run defense is tops in the NFL with 61.4 yards allowed per game as well as 2.7 yards per carry.

Miami hasn't allowed a 100-yard rusher in the last 19 games, its longest such streak since a 20-game run in 2002-03. The Dolphins limited Cincinnati to 80 yards on the ground in a 17-13 road win Sunday.

"We're getting the run shut down well and getting favorable down and distance where we can tee it up and go after the quarterback a little bit," coach Joe Philbin said. "That's only going to help us as we move forward."

Miami has recorded 11 of its 15 sacks in the last two contests and intercepted six passes in the past three. One INT came from safety Reshad Jones with 1:22 left last week to help the Dolphins rebound from back-to-back overtime losses.

While the Dolphins are making plays on defense, they'll need to cut down on their own turnovers, as they're tied for fourth in the league with 12. Rookie Ryan Tannehill has been picked off six times, though he's coming off an efficient 17-of-26, 223-yard effort against the Bengals. His 92.3 rating was a season best.

"He's getting better every single week and you can see it just in the way he puts us in the right spots, checking the plays and putting us on the right people to block," left tackle Jake Long told the Dolphins' official website. "When stuff breaks down he's able to make plays and the opponents we've faced in these first five games have been great defenses and really tough. He's handled it well and has been playing well in crunch time."

Tannehill's job could be tougher with a banged-up backfield. Reggie Bush was added to the injury report after being limited in practice Thursday with a knee injury he sustained Sept. 23, though he's yet to miss a game. Backup Daniel Thomas, meanwhile, is uncertain to play Sunday after suffering his second concussion this season against the Bengals.

Tannehill and receivers Brian Hartline and Davone Bess will face a St. Louis secondary that's recorded six interceptions -- three by newcomer Cortland Finnegan -- and has surrendered two passing TDs all season.

The Rams, winless in two road games, are 2-9 in this series. They've dropped four straight at Miami since their first visit, a 31-28 victory Oct. 3, 1976, when the team was based in Los Angeles.