One of only two undefeated teams left in the NFL, the 3-00Arizona Cardinals could endure their first blemish of the season or maintain first place in the NFC West as they take on the Denver Broncos Sunday afternoon at Sports Authority Field at Mile High.

The Cardinals put together three convincing victories before their bye week in Week 4, including the 23-14 win over division rival San Francisco even with veteran quarterback Carson Palmer sidelined with a shoulder injury the last two games. Instead, veteran Drew Stanton has taken over starting duties, and has served Arizona well with 411 passing yards and two touchdowns with no turnovers.

Given his success so far, Stanton figures to be Arizona’s starter for the foreseeable future. Palmer continues to suffer from nerve condition in his throwing shoulder, and though surgery isn’t necessary, head coach Bruce Arians said Palmer hasn’t improved since suffering the injury in Week 1, according to ProFootballTalk. That should put Stanton under center at the daunting Mile High for the first time in his career.

The lack of turnovers has certainly helped the Arizona defense stay fresh and attain their ranking as one of the best defenses in the NFL. The Cardinals are surrendering only 15 points per game, and are No. 4 versus the run, allowing 71.7 yards per game. They’re also right behind league-leaders Seattle at No. 2, letting up 2.9 yards per carry. The 18 th ranked pass defense, however, could be worrisome against Denver quarterback Peyton Manning.

Already a lock for the Hall of Fame, Manning could join the exclusive 500-touchdown pass club on Sunday, with former NFL star Brett Favre the only other passer to accomplish the feat. The 38-year-old currently sits on 499 career touchdown passes, eight of which have come this season.

But instead of making history, Manning’s mind is likely focused on getting the Broncos back on track. Before their bye week, the Broncos nearly gained some revenge on Seattle for their Super Bowl loss but fell in overtime 26-20, with Manning tossing his first interception of the season during a key drive late in the fourth quarter.

The loss also exposed the Broncos lack of a running game, and the slow development of second-year running back Montee Ball. All told the Broncos could only muster 36 total yards on the ground, and their No. 27 in rushing yards per game. Ball’s averaging 3.4 yards per carry, with undrafted second-year back C.J. Anderson making a case for more opportunities with 55 yards off 11 attempts.

Still, the game further solidified Manning’s blooming chemistry with receiver Emmanuel Sanders, even with Wes Welker re-entering fold following a suspension. The former Pittsburgh Steeler totaled 11 receptions for 149 yards off 15 targets, upping his total to 25 catches and 334 yards on the year. Welker showed little signs of rust, snagging six balls for 60 yards.

On the other side of the ball Denver’s spruced up, and expensive, defense hasn’t gelled quite yet, but there are lots of positive signs. The Broncos secondary is letting up 285.3 yards per game, but they have notched three interceptions with fourth-year safety Rahim Moore leading the way with two.

Moore, along with Chris Harris and Aqib Talib, who leads the defense with five passes defended, will tested often by Stanton and top receiver Michael Floyd and the emerging John Brown. Now in his third season and looking poised to surpass Larry Fitzgerald, Floyd is on pace to set new career-highs with 11 receptions for 252 yards. The rookie Brown went undrafted out of Pittsburg State, but the speedster leads the Cardinals with three receiving touchdowns. Fitzgerald is right in the middle with 10 receptions for 107 yards.

Start Time: Sunday, 4:05 p.m. EST

TV Channel: FOX

Betting Odds: Denver -7.5

Over/Under: 48.5 points

Prediction: Denver 27, Arizona 17