ARLINGTON, Texas - While Carson Palmer remained perfect this season as Arizona's starting quarterback, the Dallas Cowboys learned that life without Tony Romo might be a little rough.
Palmer had three touchdown passes after an early interception the Cowboys returned for a score, and the Dallas offense struggled without the injured Romo in a 28-17 loss to the Cardinals on Sunday.
The Cardinals (7-1), who have sole possession of the best record in the NFC this late in the season for the first time since 1974, won their fourth straight. They have beaten all five conference opponents.
Romo was out with his third back injury in 18 months, and backup Brandon Weeden threw two interceptions as the Cowboys (6-3) dropped their second straight after a six-game winning streak.
NFL rushing leader DeMarco Murray's record streak of eight straight 100-yard games to start the season for Dallas ended against a defense that didn't allow a back over the century mark for the 18th consecutive time. He rushed for 79 yards on 19 carries.
Palmer put his team in a 7-0 hole when undrafted Dallas rookie Tyler Patmon ducked under a route, made an over-the-head catch and ran untouched down the Arizona sideline, with some nice blocking help from defensive end Anthony Spencer.
But that was his only mistake. He finished 22 of 34 for 249 yards with touchdowns of 7 yards to John Carlson, 11 to Jaron Brown and 1 to Andre Ellington.
All three TDs came on third down as the Cardinals went 9 of 15 on third down. Palmer, who missed three games with a shoulder injury, improved to 5-0 and has won 12 of his past 14 starts.
Ellington outgained Murray on the ground with 95 yards and added another 39 receiving.
Romo was relegated to headset-wearing sideline duty with what is reportedly the same injury that kept Baylor's Bryce Petty out for a game earlier this season. It's described as fractures of two small bones in the back, and is unrelated to a herniated disk sustained last year, and to offseason surgery to remove a cyst in 2013.
Now the question is whether Romo makes the long trip to London for next weekend's game against Jacksonville before the Cowboys have their bye. If Sunday's results are any indication, Romo will be on that flight Monday.
Weeden, who left Cleveland when the Browns gave up on him just two seasons after drafting him in the first round, was off-target and out of sync with his receivers most of the game. The first completion to a wideout didn't come until the third quarter, and it was to Cole Beasley.
His first interception, by Tyrann Mathieu, came with Dallas in scoring range early in the second half. The second wiped out any hope of a comeback by the Cowboys when Antonio Cromartie stepped in front of Terrance Williams after the Cardinals had gone up 21-10 in the fourth quarter.
Weeden was sure trying to get the ball to Dez Bryant, targeting his old Oklahoma State teammate repeatedly without success until two late catches, including a 3-yard touchdown, with the outcome already decided.
The Dallas running game wasn't quite the same without Romo, either. Murray was stuffed well short on a fourth-down try from the Cardinals 34 with 9:36 remaining, and Palmer led a drive the other way for a 21-10 lead on Ellington's scoring catch.