The Cowboys (2-1), bouncing back from a 42-17 pummeling in Denver, began the game kneeling at midfield with owner Jerry Jones in a show of unity that followed widespread protests across the NFL of critical comments by President Donald Trump over the weekend.
After they kneeled, they stood and walked to the sideline.
"We planned and it was executed that we would go out and kneel," Jones said, "and basically make the statement regarding the need for unity and the need for equality."
So they decided to make their statement before the anthem.
Prescott, 13 of 18 for 183 yards, broke a 14-14 tie with a 37-yard scoring pass to Brice Butler with 11:52 to play.
Arizona, with a spectacular catch by Larry Fitzgerald for 24 yards on a third-and-18 play, moved downfield but the drive stalled. Phil Dawson's 37-yard field goal cut the lead to 21-17 with 6:35 left.
Ezekiel Elliott, who gained 8 yards on nine carries against Denver and drew criticism for not hustling after a couple of late interceptions, was bottled up much of the game, but still gained 80 yards on 22 attempts, 30 on one play. He ran 8 yards for the final Cowboys touchdown.
The Cardinals (1-2), in their home opener, got a big game from Fitzgerald, who caught 13 passes for 149 yards, in the process moving ahead of Marvin Harrison into eighth in career receiving yards. The 13 receptions tied a career high.
"That's Fitz. It's Monday night," Arizona coach Bruce Arians said. "He's a money player. It was a great performance by him. It's a shame we couldn't play better around him."
Carson Palmer had a big first half, completed 15 of 18 for 145 yards and finished 29 of 48 for 325 yards and two scores. He was sacked six times, a career-high three by DeMarcus Lawrence.
The Cardinals dominated the first half statistically, but were deadlocked with the Cowboys at 7-7. Arizona had a 152-57 advantage in yards and dominated time of possession 19:34 to 9:41.
Arizona took the opening kickoff and went 82 yards in eight plays. Palmer was 5-for-5 on the drive, capped by a 25-yard touchdown pass to Jaron Brown.
Before Dallas even had a first down, Arizona mounted a nearly nine-minute drive but a touchdown pass to Brown was negated by a holding penalty and Phil Dawson's 36-yard field goal try was wide right. It was the third mid-range miss for the 41-year-old kicker this season.
And the miss left the door open for the Cowboys to get back in it.
Prescott scored on a 10-yard run, flipping head-first over the goal line to tie it at 7-7 with 3:33 left in the half.
