The Arizona Cardinals' unbeaten start to the 2015 NFL season has ended after they suffered a 24-22 defeat at the hands of NFC West rivals the St Louis Rams.

The Cardinals were under pressure from the start as Daren Bates fumbled the opening kickoff, gifting possession to St Louis at the Arizona 17, which allowed Nick Foles to pick out Tavon Austin for a touchdown on the next play.

Carson Palmer struggled to connect with his receivers in the first quarter, and was sacked for the first time this season, but the quarterback did get the team into field goal range twice, leaving Chandler Catanzaro to keep the home side in contention.

Palmer looked to find John Brown with a deep pass to the endzone for a touchdown midway through the second quarter, but Janoris Jenkins beat the wide receiver to the ball, handing possession back to the Rams.

Greg Zuerlein briefly gave the Rams a four-point advantage as half time approached, but Catanzaro added another kick before the break to leave the NFC West leaders just a point down at the interval.

The Rams defense made a big play early in the third quarter, forcing a fumble from Larry Fitzgerald, which set up Foles to fire the ball deep the Stedman Bailey for St Louis's second touchdown of the game.

After Catanzaro converted another field goal for the Cardinals, the kicker appeared to pick up a knock after taking a heavy hit on the kickoff, but he was still able to boot the ball away for the home side.

First-round Draft pick Todd Gurley looked to get into a position to score his first NFL touchdown, but the running back fumbled the ball after being tackled by Tyrann Mathieu, although the Arizona safety could not keep hold of the ball, allowing Rob Havenstein to recover it for the Rams.

Catanzaro recovered from his hit to close the gap to two with another field goal, but Gurley made amends for his fumble soon after with a blistering 52-yard run, leaving Foles with a short pass to Austin to put St Louis nine points clear.

The home side kept pressing to get back into the game though, with Fitzgerald hauling in a big catch to set up David Johnson for a rushing score, leaving Arizona just two points behind, but Gurley ensured that the Rams kept hold of the ball for the remainder of the game.

The result keeps the Cardinals at the top of their division with a 3-1 record, while the Rams improve to 2-2.