Just when Arizona's fortunes had turned sour, along came Kerwynn Williams, an unlikely hero.

Williams provided what quarterback Drew Stanton called the "shot in the arm" the Cardinals needed on Sunday in Arizona's 17-14 victory over the Kansas City Chiefs.

The Cardinals (10-3), who had lost two in a row, needed the win to stay a game ahead of Seattle in the NFC West. Now they have a short week to prepare for a Thursday night contest at St. Louis.

"You've got to love NFL scheduling," Arizona wide receiver Larry Fitzgerald said.

The Chiefs (7-6) dropped their third straight and trail three teams in the AFC wild card chase.

"We obviously need to do a better job, take care of our business," Kansas City coach Andy Reid said. "It's my responsibility that takes place. We had e very opportunity to do that today, and we didn't get it accomplished."

On Friday, Williams practiced with the scout team, pretending to be Jamaal Charles. Afterward, coach Bruce Arians told him he was being elevated to the regular roster.

Williams responded by rushing for 100 yards, nine more than Charles got. The former Utah State back, a seventh-round draft pick by Indianapolis last year, was the main cog in a running game that had been so bad lately. After rushing for fewer than 100 yards in the last two games combined, the Cardinals got a season-high 141 on Sunday.

"Quickness, explosiveness, an unbelievable change of direction," Arians said of Williams. "He can break a guy down in a hole and make him miss and he's got power for a smaller guy."

Williams' big game came the same day that Arians said running back Andre Ellington's season is over. Ellington is to have surgery to repair a hernia. He never had been at full strength this season.

Arians gave Williams a game ball. Williams said he would give it to his parents.

Some things to know from the Cardinals' win:

CONTROVERSIAL CALLS: The Chiefs were on the wrong end of a couple of controversial calls in the second half.

"The refs called two plays that I think were just crazy," Kansas City running back Jamaal Charles said.

First, a third-quarter touchdown was negated when tight end Anthony Fasano was called for offensive pass interference. On the next play, an interception ended the threat and led to Arizona's lone touchdown.

"My back judge (Lee Dyer) reported to me that he had Fasano blocking," referee Craig Wrolstad told a pool reporter, "blocking downfield to create separation which allowed him to be open for the pass."

In the fourth quarter, Arians challenged a call that tight end Travis Kelce was down by contact after a 19-yard pass reception to the Arizona 22. After the review, the call was reversed, giving the Cardinals the fumble recovery at the 15.

"The tight end caught the ball, took a number of steps, got hit and as he was going to the ground, the ball came loose. The ball remained loose. ... He tried to maintain possession, but he did not."

ARIZONA'S DEFENSE: After surrendering 500 yards in its worst performance of the season last week's 29-18 loss to Atlanta, the Arizona defense came back to shut out the Chiefs in the second half after they had taken a 14-6 halftime lead.

"This is the story of our season," said linebacker Alex Okafor, whose interception stopped a Kansas City drive and led to the Cardinals' lone touchdown. "Playing hard in the first half, but cranking it up in the second half, especially at home."

Arizona has blanked the opponent in the second half of its last three home games.

CHARLES TURNS QUIET: Jamaal Charles broke loose for a 63-yard touchdown run, then caught an 18-yard touchdown pass from Alex Smith.

In between, he went down with a left ankle sprain. Reid called it a mild sprain.

"It was scary at first," Charles said. "I thought I tore it up.

In the second half, Charles rushed for 17 yards in seven carries.

HOME COOKING: Arizona improved to 7-0 at home, the most home victories for the franchise in the 16-game era.

It's also the most since the Chicago Cardinals won 11 of 13 home games in 1925.

The Cardinals are 13-2 at home since Arians became coach.

TURNOVERS: Arizona won the turnover battle 2-0, with an interception and fumble recovery.

The Cardinals have a plus-10 turnover ratio. They have 17 interceptions.

Kansas City has a minus-six turnover ratio.

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