Cardinals running back David Johnson stiff-arms a Chargers' defender during Arizona's 22-19 preseason loss Saturday night.

Chris Johnson wasn't available after all, tweaking his hamstring on the final practice of the week during a training camp of hamstring tweaks.

So it turned out the lone running back to make his Cardinals debut in Saturday night's preseason game against the San Diego Chargers was third-round pick David Johnson. And after his own hamstring problem undercut a chunk of training camp – and garnered some tough talk from coach Bruce Arians – the rookie displayed the skills the Cards hoped he would add to the offense.

Johnson ran for 66 yards on 13 carries and caught two passes for 15 yards in the Cardinals' 22-19 loss at University of Phoenix

Stadium, after Arians once again delivered a message.

"After he quit dancing and got out of the dance studio, I thought he played real well," Arians said. "He's powerful and fast and he learned quickly not to dance."

"We had a nice talk about dancing," Arians added.

Johnson smiled when asked about it, saying that Arians just reminded Johnson he wasn't in college anymore.

"It took me a while to get a feel for that game," Johnson said, and after a while, "I started reading the holes a little bit more."

It's a good place to have Johnson, since Chris Johnson is out a week or two with his hamstring pull. Between Johnson and Andre Ellington, the Cardinals averaged five yards per rush in the first half.

The game didn't end the way the Cardinals wanted, with a solid fourth quarter by rookie Phillip Sims wasted when the Chargers kicked a game-winning field goal on the final play – breaking a tie only after the Cards kicked their own field goal after squandering what could have been a touchdown drive late.

But the Cardinals also got want they wanted from the starters. Quarterback Carson Palmer absorbed his first hits of the preseason since his ACL surgery, including a pair of sacks. But he hooked up with rookie speedster J.J. Nelson on a beautiful 57-yard bomb to set up the Cards' first touchdown – which came a couple plays later when Palmer threw a perfect 17-yard strike to John Brown in the back of the end zone. Palmer finished 3-for-7 for 88 yards.

"We have to finish when we get into the red zone," Brown said. "We made some mistakes we usually don't make, so when we get there we just have to punch it in."

The Cardinals (0-2) surrendered six sacks, and the Chargers (2-0) scored their lone first-half touchdown after backup quarterback Drew Stanton tried a play-action pass to tight end Troy Niklas but instead threw it right to linebacker Kavell Conner. Conner returned it to the Arizona 12-yard line to set up their score.

The Chargers didn't play starting quarterback Philip Rivers, but the Cardinals' starting defense only allowed 31 yards and one first down on three San Diego possessions.

"We were efficient," safety Rashad Johnson said. "We knew (Rivers) wasn't out there so we were like, 'We're going to get a lot more checkdowns, we won't have as many throws down the field as we would with (jersey) 17 in the game.' And that's pretty much exactly what we got."

Still, the Chargers eventually built a 19-9 lead before Sims directed his rally. Sims was 8-for-13 for 82 yards, while Logan Thomas was 0-for-4, but Arians said there still is no real leader for third quarterback. Both players missed chances at touchdown passes because of errant throws.

Arians praised some young players besides Sims, too, noting linebacker Alani Fua, cornerback Cariel Brooks and defensive lineman Josh Mauro.

And, of course, Johnson, who may have the best chance to make the biggest impact. He just needs to listen to Arians, who told him "stick your foot in the ground and give me four yards and more will come."

"You run side to side it's harder to gain yardage," center Lyle Sendlein said. "Sometimes it takes guys a long time so you have to be happy David figured it out in a series or two."