(My Sportsbook) - A pair of AFC Super Bowl contenders put their 4-1 records on the line this Sunday in Denver, where the Broncos will play host to the first-place Miami Dolphins in prime time clash between conference heavyweights.

Both teams rebounded from ugly Week 4 losses with impressive victories last Sunday, and Miami's 26-13 win over the New England Patriots vaulted the Fins into the top spot in the AFC East. Denver thrashed the formerly unbeaten San Diego Chargers last week, recording a 26-9 triumph to stay within striking distance of the red-hot Oakland Raiders in the West.

While each team has been performing well on offense, its their defensive effort that has been the main reason for their success. Miami smothered Tom Brady and the Pats, while the Broncos held San Diego RB LaDainian Tomlinson to a season-low 48 yards.

This week's game has the makings of a classic, and could represent a potential playoff preview. Confidence is running high on both sides, but only one team can come away with the all-important victory.

Denver coach Mike Shanahan believes his defense has played as good as he's ever seen, owning the second-best rush defense in the NFL. After shutting down Tomlinson last week, the focus shifts to Miami's Ricky Williams, who pounded the ball 36 times for 105 yards against New England in Week 5.

After losing to Baltimore on Monday night in Week 4, the Broncos had to take a long, hard look in the mirror. They needed to make a statement against the Chargers in order to get their confidence back, and that's what they did. Denver shut down San Diego's heralded running game, and regained its mental edge.

"We had a mask on Monday night in Baltimore," linebacker John Mobley said after Sunday's win. "I don't know who those imposters were, but we got our swagger back."

Denver's run defense will be tested again this week by Williams, who owns the second best per-game average in the NFL (113.0 ypg). Since the Broncos got an up close and personal look at Tomlinson (110.8 ypg) last week, they will be well prepared for Miami's spark plug.

"It was really just being sound in our gap-control," Mobley said. "[Tomlinson is] a cut-back runner. He tries to find little creases and slither through them, and I think everybody did a good job maintaining their gap responsibility."

Williams is a similar rusher to Tomlinson, and the Broncos would love to keep the former Heisman Trophy winner under 75 yards.

Denver has been setting the standard for producing 1,000-yard backs for the better part of a decade. Now there's a new face in the backfield but the results are the same. Rookie RB Clinton Portis leads all first-year backs with 306 yards on 55 carries (5.6 ypg) and had a great game last week. Against San Diego's historically solid rush defense, the Miami product gained 102 yards on a season-high 20 carries.

"Coming in as a rookie you've got to wait your turn," Portis said. "I finally got my opportunity to play and I was going to take advantage of it."

"[Coach Shanahan] said, 'We're going to go with you, rook, so be ready,'"

Shanahan has made it clear that Portis will be the No. 1 back, and Mike Anderson and Olandis Gary will only see action in the rotation to keep all three fresh. But all three are still a threat to break a long run.

"I think everybody can see what type of ability [Portis] has," Shanahan said. "He's quick, he's fast, he's got some big-play potential, and I think he'll get better each game. I think he'll get more of a feel for NFL defenses, what he can do when he's inside the tackles, what he can do when he's outside the tackles, so I think he'll get better as time goes on."

Don't forget, Portis had some serious fumbling problems in the preseason, and Miami's defense creates a lot of turnovers.

COMING UP: The Broncos travel to Kansas City for a meeting with the Chiefs in Week 7.