Cardinals quarterback Carson Palmer, here calling out the linebackers before a play, suffered a left arm injury in Sunday's loss.

LONDON, England – The week-long business trip across the Atlantic Ocean ended about as badly as it could have for the Cardinals.

Not only did they lose a key NFC West game to the Los Angeles Rams Sunday night at Twickenham Stadium, but they lost quarterback Carson Palmer – probably for the season – with a broken left arm when he was crushed throwing a pass.

"That's a real gut punch," wide receiver Larry Fitzgerald said quietly, after the Cardinals were shut out, 33-0. "To lose your best offensive player, your quarterback, there's no positive way to sum it up. You say you have to go forward, but it's a tough pill to swallow."

Coach Bruce Arians said Palmer would undergo surgery and be out eight weeks. Drew Stanton, who came in in relief Sunday, will be the starter for the rest of the season, Arians said. Asked if there was a way he might consider starting Blaine Gabbert at some point, Arians said no.

Why? "He's No. 2," Arians said. "You don't skip 2 to go to 3."

The sequence in which Palmer was hurt was a microcosm for the forgettable evening. After getting great

pass protection most of the first quarter-and-a-half, Palmer was belted by linebacker Alec Ogletree as he tried to maneuver around a collapsing pocket. Palmer was in the process of throwing deep to J.J. Nelson, and the resulting floater was an east fly ball interception for cornerback LaMarcus Joyner.

The ball was returned to the Arizona 18-yard line, and the next play Rams running back Todd Gurley burst off the left side and down the sideline for an 18-yard touchdown run.

It only made the score 13-0, but it effectively cemented the tone for the game. The Cardinals (3-4) had a good opening drive, even without much of a running game, but when it stalled, kicker Phil Dawson missed a 32-yard field goal, his fifth miss of the season. It was a hiccup the Cardinals did not need, and, as it turned out, an omen.

It was the first time the Cardinals had been shut out since losing, 58-0, in Seattle in 2012 and was the second straight blowout loss on the road after falling, 34-7, in Philadelphia two weeks ago.

Arians said he didn't know why the games had gone so sideways away from home.

"Wish I knew," Arians said with a wistful chuckle. "I'd sell it."

[READ: LONDON -- AND PALMER -- AFTERMATH]

With the Rams keying on Adrian Peterson, the running back never came close to repeating his first-week success. Reduced to few snaps once the deficit grew, Peterson gained just 21 yards on 11 carries.

The Cardinals made their change in the secondary, replacing cornerback Justin Bethel in the starting lineup with Tramon Williams. Bethel, in fact, was relegated to special teams as Williams got the call.

But the Rams (5-2) – under new coach Sean McVay – continued their upswing on offense. Gurley was very

good, gaining 106 yards rushing and adding 48 yards on four receptions. Quarterback Jared Goff did throw an interception, picked off by money linebacker Deone Bucannon, but the Cards never capitalized.

"At some point we have to take ownership of how we play," safety Tyrann Mathieu said. "We have to find a way to put the fire out. Football is a game of momentum. That may not show up on the stat sheet."

The Cardinals will have to do it without Palmer. It was the third time Palmer, as a Cardinal, has been hurt against the Rams. He tore his ACL against them in 2014, he suffered a concussion against them in 2016 and now a broken arm.

Stanton has led the Cardinals for long stretches before – in 2014, for instance – and the team did make the playoffs. But for a team already struggling, going to the backup will take an adjustment. The Cardinals are on a bye this week, and then play in San Francisco.

"My heart goes out to (Carson) and really, this team, for losing a potential Hall of Famer," Stanton said. "It's tough. Unfortunately that's what happens in this league. Injuries happen and you have to pick up the pieces."

Stanton only completed 5-of-14 for 62 yards and an interception. Arians said the situation was unfair to Stanton since he didn't practice much during the week, but Stanton waved that away, saying it was his job to be prepared.

Stanton called Palmer the "toughest individual I've ever been around," and said Palmer actually tried to come back in the game. Stanton said he was in a "will he or won't he" situation for a moment, before the bad news was delivered.

"Quarterback is one of those positions where 'next man up' is far-fetched," Mathieu said. "We've got to protect the football and create more turnovers."

It was not the kind of London experience the Cardinals had been hoping to have.

"The intensity wasn't there, the urgency that you need to beat good teams wasn't there," Fitzgerald said. "To travel all this way and to do everything you felt you needed to prepare to win this game and then lay an egg is frustrating and disappointing."