Kansas City, Mo. ? The Kansas City Chiefs gained a much-needed victory – and greater respect for the courage of officials viewing instant replay.

Reversing a crucial call on the field, referee Bill Leavy took a first down away from Denver near midfield with 2:01 to play. The Chiefs, relieved of the danger of facing a final threat from the Broncos’ offense, ran the clock down to three seconds and danced away with a 31-27 victory.

“Sometimes it’s just a lot easier for them to go with the flow of the game and not make the big reversal,” said Chiefs guard Brian Waters. “I think that was a gutsy call.”

The win brought the Chiefs (8-4) within one game in the AFC West of the Broncos (9-3), who had won four in a row and could have buried Kansas City in the division. Instead, the Broncos have a fight on their hands and are left with virtually no chance of overtaking unbeaten Indianapolis for the top seed in the AFC.

“This is a big win for us,” Chiefs coach Dick Vermeil said. “A big, significant win.”

Mike Anderson, on fourth-and-one from the Denver 47, plunged into the right side of the line.

Officials on the field gave him a first down, and Chiefs players went into a frenzy of protest over the spot, particularly cornerback Patrick Surtain.

Kansas City's Jared Allen (69) celebrates after the Chiefs defense stopped a Denver scoring drive on downs late in the fourth quarter. The Chiefs won, 31-27, Sunday in Kansas City, Mo.

“You saw me going berserk out there,” said Surtain, who earlier intercepted Jake Plummer’s pass from the K.C. four.

“I was saying, ‘It’s our ball, it’s our ball.'”

A few minutes later, the call was reversed.

“It was clear to me he didn’t reach the first down, and the right thing to do was reverse it and give the ball to (Kansas City),” Leavy said.

When the Broncos got the ball back, they had time for one desperate heave as the Chiefs won their 17th straight home game in December.

Defensive end Jared Allen, who made the tackle with help from Lionel Dalton, was confident the spot was wrong.

“I knew when I hit him he didn’t make it,” Allen said. “I ran right down the line and hit him backward. It was no contest.”

The Broncos watched helplessly as their offense was forced to leave the field.

Kansas City linebacker Kawika MitchelL, center, intercepts a pass from Jake Plummer as Dexter McCleon, right, closes in on the play. The Chiefs edged the Broncos, 37-34, Sunday in Kansas City, Mo.

“I didn’t see what happened. I thought we had a first down,” Denver coach Mike Shanahan said.

Trent Green threw two touchdown passes and Larry Johnson rushed for 140 yards and two more scores for the Chiefs, who have won four of last five to climb back into contention.

Plummer, who went 229 passes without an interception until the Dallas Cowboys got one last week, also was picked off by Kawika Mitchell on his first throw of the second half.

“We had opportunities we didn’t take advantage of,” said Plummer, 18-of-29 for 276 yards and one TD. “If you do that on the road, and at a place like this, you are going to end up on the wrong side of the win-loss column.”

Following Mitchell’s interception, Lawrence Tynes kicked a 34-yard field to put Kansas City up 24-21, but Jason Elam tied the game with a 22-yarder.

After Darrent Williams intercepted Green’s pass on the Chiefs’ next possession, Elam kicked a 40-yarder to put the Broncos on top, 27-24.

Johnson, with his fifth straight 100-yard game, scored on a 4-yard run to make it 31-27 with 9:58 left.

Eddie Kennison caught four passes for 108 yards for the Chiefs.

On the Broncos’ second play, Anderson took Plummer’s pass in the flat and went 66 yards, putting a move on Greg Wesley in the middle of the field that left the Chiefs’ safety face-down in embarrassment.

After the Chiefs took a 14-7 lead, Anderson scored on a 1-yard run.

Dante Hall got behind Denver cornerback Champ Bailey in the first half, and Green hit him with a 41-yard TD pass. Kennison had a 54-yard catch on the Chiefs’ next possession and Larry Johnson scored from the 1.

Kennison had a 27-yard catch to set up Green’s 25-yard TD pass to Tony Gonzalez for a 21-14 lead, which the Broncos erased with 22 seconds left in the half on a trick play.

Second-year reserve quarterback Bradlee Van Pelt lined up behind center as Plummer was flanked left on second-and-goal from the seven. Van Pelt took the snap and went almost untouched into the end zone for a TD on his first NFL play.

Notes: Johnson’s fifth straight 100-yard rushing game tied a club record set by Priest Holmes in 2002. His 470 yards in the last three games is the best three-game total in team history. … Denver has had five streaks of three or more wins broken at Arrowhead Stadium since Shanahan became head coach in 1995. … Chiefs DT Ryan Sims, out since the season opener with a foot injury, saw limited action.