The changing of the guard is complete tonight. The Steel Curtain finally has been closed for good. A 24-year-old who grew up rooting for the Dallas Cowboys -- and against the Pittsburgh Steelers while they won four Super Bowls -- has stolen a pass from John Elway, a game from Denver and the hearts of underdogs everywhere.

Pittsburgh free safety Eric Williams, in his second year from North Carolina State, stepped in front of Elway's pass to Ray Alexander at the Denver 30 with less than three minutes to play in a tied game and returned the ball 28 yards to the two.

Three plays later, Frank Pollard twisted through the middle of the line for a two-yard touchdown with 1:59 remaining to give the Steelers an improbable, come-from-behind, 24-17 victory before 74,981 at Mile High Stadium.

The Steelers (10-7 overall), who upset the Los Angeles Raiders two weeks ago just to qualify for the playoffs, will travel to Miami to play the Dolphins for the AFC championship Sunday. If they win, it will be their first appearance in the Super Bowl since 1980, when they won their last of four NFL titles.

The Broncos, champions of the AFC West, finished their season 13-4.

"It's a first for me," said Williams, who lists Lifetime Thrill No. 2 as "making the Steeler team" as a rookie. "I don't think Elway saw me."

He didn't. "When I looked at Ray, he was open," said Elway, who played the fourth quarter with a bruised knee and pulled groin, neither of which is considered serious. "I knew I was hurt, but I wanted to stay in and try to help the team."

Instead, the interception helped get the Steelers off the hook. With 3 1/2 minutes remaining and the score 17-17, their kicker, Gary Anderson, missed a 26-yard field goal, giving the Broncos a chance to win. But Elway was intercepted on the second play.

"You're sitting there, on the edge, all nerves," said Pittsburgh nose tackle Gary Dunn, "and then somebody comes up with the big play."

The Steelers, playing a much more aggressive, pressing defense than they did earlier in the season, were blitzing their outside linebackers on Williams' interception.

"Then they have to throw to their hot receiver," Coach Chuck Noll said. "They have to get rid of the ball quickly."

Williams plays center field. Elway stared at Williams, then looked away. "He was trying to keep me honest," Williams said.

Then he threw a hard, low fast ball to Alexander. "When he went to 80, I went to 80," said Williams, who cut right in front of No. 80 and cut across the field, nearly rolling into the end zone.

For the touchdown, the Steelers went to their "old reliable" short-yardage play, center Mike Webster said, one they use 85 percent of the time in this situation.

Pollard, who gained 99 yards and scored two touchdowns, was stopped inches short of the goal line, but, said quarterback Mark Malone, "He kept those monster legs of his churning."

The result was the most unexpected of all four conference semifinal games. Pittsburgh, the only team to beat San Francisco this season, had a 7-7 record with two weeks remaining in the regular season.

"Our opponents are all supposed to be the teams," Williams said. "They're calling us the nothing team, saying we shouldn't be in the playoffs.

"When people talk about you, you get mad."

The Steelers overcame consecutive fumbles by Malone early in the game and a blocked punt deep in their territory early in the second half.

They took the lead for the first time, 10-7, with 1:14 remaining in the first half on Pollard's one-yard run. The 78-yard drive was anchored by Pollard, who gained 44 yards on three carries before the touchdown run.

That ended a half full of frustrations for the Steelers. After Denver punted on its first possession, the Steelers kept the ball for three plays before Malone fumbled on a sack by Rulon Jones. Andre Townsend recovered at the Pittsburgh 23, but the Broncos gained only one yard in three plays before Rich Karlis missed a 39-yard field goal attempt.

On the next Pittsburgh play, Malone, trying to change the cadence of the snap count to confuse the defense, muffed the snap and linebacker Tom Jackson recovered at the Pittsburgh 22.

This time, Denver scored when H-back Jim Wright juggled a nine-yard pass to give Denver a 7-0 lead with 6:30 left in the first quarter.

It was the first time in 14 games the Steelers had allowed a first-quarter touchdown.

The Steelers answered with a drive from their 27 to the Denver 11 for Anderson's 28-yard field goal on the first play of the second quarter.

Denver nearly scored again on its next drive, but, from the six on third and goal, Elway's floater intended for Winder wound up in Dunn's hands at the four.

Dunn, who was looking for Elway to roll out and had moved off the line, returned the interception to the 10.

The Broncos quickly piled up 10 points as tempers flared in the third quarter, but the Steelers came back to tie the score, 17-17, on Malone's 10-yard pass to Louis Lipps with 3:13 remaining in the quarter.

Roger Jackson blocked Craig Colquitt's punt at the Pittsburgh four-yard line in the first minute of the second half, giving the Broncos a first down at the four.

But they had to settle for Karlis' 21-yard field goal to tie the score.

On their next possession, starting at the Pittsburgh 46, Elway completed three of four passes for 36 yards on a neatly packaged touchdown drive.

Steve Watson, who caught 11 passes for 177 yards, finished it with a 20-yard touchdown reception midway through the third quarter to put Denver in front, 17-10.

But the Steelers came right back with their next-to-last touchdown to tie the score again.