LONDON -- Cardinals quarterback Carson Palmer broke his left arm in the 33-0 loss to the Los Angeles Rams at Twickenham Stadium on Sunday, leaving Drew Stanton to take over after the team returns from its bye week.
Palmer will require surgery on the arm and coach Bruce Arians said he expects the quarterback to miss eight weeks.
That leaves Stanton, who has been Palmer's backup since the two joined the team prior to the 2013 season, to step in and lead the offense.
And while the 10-year veteran has handled that role capably in the past, he completed just 5 of 14 passes for 62 yards and an interception in the Cardinals' first shutout loss since Dec. 9, 2012.
"You never want to see something like this happen, especially to Carson," Stanton said. "We've been together for five years. My heart goes out to him. For this team losing a guy like that, a Pro Bowler and potential Hall of Famer, it's tough -- and losing a friend and a teammate.
"Unfortunately, that's what happens in this league. Injuries occur and you have to pick up the pieces and move on, because nobody is going to feel sorry for you."
Palmer was attempting a deep throw to wide receiver J.J. Nelson with 5:48 remaining in the first half when he took a hard hit from Rams inside linebacker Alec Ogletree.
That hit led to an interception that free safety Lamarcus Joyner returned 29 yards, and Palmer, who finished 10 for 18 for 122 yards and the interception, slowly walked off the field holding his left arm close to his chest following the play.
Stanton entered the game with the Cardinals (3-4) trailing 13-0, and after his first drive went just 17 yards in seven plays, his first attempt on the next drive, with 41 seconds remaining in the first half and Arizona at its own 25-yard line, was intercepted by inside linebacker Mark Barron.
"You don't want to hurt anybody, but when you get that quarterback out, you mess up the rhythm of the game," said Rams defensive tackle Michael Brockers. "I think we took advantage of it today."
Stanton, who has appeared in 33 games and made 13 starts in his 10-year career, stepped in when Palmer tore the ACL in his left knee in Week 6 in 2014 -- though a knee injury of his own ended Stanton's run after five starts.
He also made a spot start last year, when a concussion left him unable to play the San Francisco 49ers in Week 5.
"That's a real gut punch to lose your best offensive player, your quarterback" receiver Larry Fitzgerald said. "There's no really positive way to sum it up, honestly. You say you have to go forward and you have to do things, but we all know that's a tough pill to swallow for us."
The Cardinals also have Blaine Gabbert, who started 13 games for the 49ers the last two seasons, but he has been the inactive third quarterback for each of their first seven games.
When asked if he would consider turning to Gabbert instead of Stanton based on Sunday, Arians said no.
"We played with Drew before, you know," Arians said. "Drew's played and won a lot of games for us. All the confidence in he and Blaine to step up and take over the quarterback job."
PETERSON SHUT DOWN
Adrian Peterson, in his second game for the Cardinals since being acquired via a trade with the New Orleans Saints, was held to just 21 yards on 11 carries.
It was a contrast from a week ago, when he ran for 134 yards and two touchdowns in a win over the Tampa Bay Buccaneers.
Kerwynn Williams handled the bulk of pass-protection duties with Andre Ellington out because of a quadriceps injury, but he did not have a rushing attempt.
With his first catch, a 16-yard reception over the middle on the fourth play from scrimmage, Arizona wide receiver Larry Fitzgerald has now caught a pass in the NFL in 40 different stadiums.
Fitzgerald finished with just three catches for 29 yards.
In addition to Palmer, the Cardinals lost two players to injury who later returned: inside linebacker Karlos Dansby (left hand) and defensive tackle Frostee Rucker (right knee).
Cardinals will have their bye week before visiting the San Francisco 49ers on Nov. 5.