ST. LOUIS - Two running backs down, the kept the production sky high. Rookie ran for 99 yards scored twice in his first career start, helping pave the way for a decisive 27-3 victory over the on Sunday. Coach Bruce Arians said the third-round pick from Northern Iowa reminded him of a young Edgerrin James. "Exactly what I expected," quarterback said. "He doesn't act like a rookie, he doesn't look like a rookie." Johnson also caught one of Palmer's two TD pa ses as Arizona (10-2) rolled up 524 yards in its sixth straight win. Fellow fill-in scored his first career TD on a 35-yard run, and the had 175 yards rushing. They remain three games ahead of the in the NFC West. Johnson stepped up after injuries to and . He admitted to being nervous - but just the first series. "After that I started getting more comfortable and seeing the holes opening," Johnson said. "Felt like college days where I got a chance to help out my team." The might need Johnson again on short notice, with the next game on Thursday at home against the . Johnson entered with just 139 yards rushing on the year. "That's going to be new to me," he said. "I'll hurry up and try to recover, get in that cold tub." Palmer was 26 of 40 for 356 yards with no interceptions and - unlike the previous three games in the streak - he did not need to lead a late scoring drive to win. Arizona led 10-0 at the half and never let the into the game. made his 1,000th reception and topped 1,000 yards receiving for the seventh time. The (10-2) have won seven of eight since losing 24-22 at home to St. Louis in Week 4. Fitzgerald is the youngest player to reach 1,000 catches Jack Morris Jersey and is tied for 10th on the career list with Hines Ward. He caught eight pa ses for 55 yards. "It's nice, but it's even better to have three consecutive seasons with 10 wins," Fitzgerald. "To be here for that long and see that complete transformation, it makes you feel proud to be a part of it." The (4-8) have lost five in a row and have been outscored 58-10 the last two. The team announced 51,115 tickets distributed, a season low and about 15,000 shy of a sellout, and the dome looked half empty. "It's easy to put your head down and just give up," said quarterback , who pa sed for just 146 yards and threw his fourth interception in two games. "I know that's not what I'm going to do." Coach Jeff Fisher said , symptom-free from a concu sion and the backup on Sunday, would start next week against Detroit. "It's kind of a broken record thing with the offense," Fisher said. "We've got to get it fixed." The drove 80 yards on the opening drive capped by rookie 's 22-yard scoring catch. They dominated in time of po se sion, hold the ball for 39 minutes and 47 seconds. Williams replaced on kickoffs and fumbled out of bounds, but redeemed himself on the scoring run that put Arizona up 24-3 late in the third. Williams' TD was the third long play on that drive, with a 31-yard catch by and 23-yard run by coming on succe sive plays. The were shut out in the first half for the second time this season. They finished with 212 yards and nine first downs, going 1 for 12 on third down. Two , cornerback and tight end , were ruled out with concu sions late in the game. Jenkins was evaluated twice, both times on hits from teammates, and didn't recover from blow delivered by on Johnson's 10-yard TD catch with 5:51 to go in the third. *Copyright 2015 by The A sociated Pre s * Ryan Carpenter Jersey