The sixth-round draft pick from Clemson rushed for 154 yards on 15 carries, including an 80-yard touchdown run, and the Arizona Cardinals intercepted Matt Ryan four times in a 27-13 victory over the Atlanta Falcons on Sunday.
Ellington's big run, tied for third-longest in Cardinals history, was part of a 21-point second quarter that put the Cardinals (4-4) in control for good.
Arizona's Larry Fitzgerald caught four passes for 48 yards and a touchdown, in the process becoming the youngest player—at 30 years, 57 days—in NFL history to reach 800 career receptions.
Ryan had thrown three interceptions total in the first six games of the season for the Falcons (2-5).
The Cardinals picked off Ryan five times when the teams played last season.
Ellington got the start because Rashard Mendenhall was sidelined with a toe injury.
The Falcons were without wide receiver Roddy White for the second week in a row with ankle and hamstring issues. Atlanta also didn't have starting left tackle Sam Baker with a knee injury.
After throwing his 14th interception of the season, Carson Palmer had two TD passes, 10 yards to Fitzgerald and 15 yards to Michael Floyd. He was sacked four times.
Steven Jackson, back for the first time since being sidelined with a hamstring injury in Week 2, managed just 6 yards on 11 carries.
In all, the Cardinals gained 201 yards on the ground to Atlanta's 27.
With no running game, it was up to Ryan, who completed 34 of a season-high 61 attempts for 301 yards and a touchdown. Harry Douglas had 12 catches for 121 yards.
Asante Samuel stepped in front of intended receiver Andre Roberts for his 51st career interception, giving Atlanta the ball at the Arizona 31. The Falcons advanced to the Cardinals 6, but Ryan's third-down pass intended for Jackson fell incomplete and Matt Bryant's 24-yard field goal put Atlanta up for the only time of the afternoon, 3-0.
The Cardinals took the kickoff and Palmer threw 51 yards to Teddy Williams, a speedster who had signed with Arizona on Tuesday. Williams, who didn't play college football, played in seven games for Indianapolis last season on special teams and as a defensive back.
That set up Palmer's 10-yard TD pass to Fitzgerald on the first play of the second quarter and Arizona led 7-3.
Atlanta used up 7:17 on a 15-play drive but had to settle for Bryant's 30-yard field goal to cut the lead to 7-6.
On the first play after the subsequent kickoff, Ellington followed blockers through the left side of the line, then burst outside and raced the length of the field for the touchdown, putting Arizona up 14-6 with 7:25 left in the half.
Atlanta went three-and-out on its next possession, and the Cardinals moved downfield again.
Palmer threw 20 yards to Fitzgerald and Desmond Trufant was called for a facemask, moving the ball to the 35. Stepfan Taylor broke a pair of tackles on a 15-yard run to the 17. Two plays later, Palmer threw 15 yards to Floyd for the touchdown and Arizona led 21-6 with 1:52 left in the half.
All four of Ryan's interceptions came in the second half.
Early in the third quarter, Daryl Washington intercepted Ryan's pass and returned it 8 yards to the Atlanta 22. Jay Feely's 39-yard field goal put the Cardinals ahead 24-6 with 7:07 left in the third.
Rookie Tyrann Mathieu's interception led to Feely's 38-yard field goal that made it 27-6 with 8:40 to play.
Arizona led 27-6 before Ryan's 4-yard touchdown pass to Drew Davis with 4:37 left. The Falcons' Matt Bosher recovered the onside kick at the Atlanta 48. Calais Campbell's sack and a false-start penalty left Atlanta in a fourth-and-20 situation and Johnson got his second interception.