The Pittsburgh Steelers are the most unlikely Super Bowl contenders. Their quarterback, a midseason throw-in because of an injury, has the week-long beard and tobacco-stained teeth of a guy who just walked off the night shift at the mill.

They almost lost their playoff spot to a .500 team, the Cincinnati Bengals. Their star running backs come from Baylor, not exactly known as a running back factory. And their resident graybeard, a 32-year-old balding center who has four Super Bowl rings, refuses to show even one.

"That's past history," Mike Webster said after the Steelers upset the Denver Broncos, 24-17, Sunday at Mile High Stadium.

"This football team needs to win its first."

Reality says that probably won't happen this season. The Steelers will play Miami in the Orange Bowl Sunday at 12:30 p.m. to decide the AFC championship, and it's difficult to imagine the Steelers winning that game.

Miami beat Pittsburgh, 31-7, in Dan Marino's homecoming at Three Rivers Stadium Oct. 7.

"We've got another shot at them," said quarterback Mark Malone, who replaced injured David Woodley in the middle of the season. "They're good, but we're one game from the Super Bowl and that should fire us up."

Added Webster, one of only three active players from the team's Super Bowl years: "We've got to control the ball and keep Marino off the field. We'll have to play a great game and let our intensity take care of itself."

Denver, meanwhile, is a city in shock. The Denver Post ran 20 stories on the game, not counting a fan hotline column in which one of the few mild-mannered fans who called in suggested the Broncos' loss should boost attendance for the NBA's Denver Nuggets.

This was a certain victory, fans here thought. A columnist for the Rocky Mountain News wrote the day of the game that to spell Pittsburgh running back Frank Pollard's name, you wrote "S-T-I-F-F," and referred to running back Walter Abercrombie as "some guy named Abacrumbie."

"They were already on their way to Miami when they came out of the locker room," Pittsburgh cornerback Sam Washington said. "They didn't even think they had to play us."

For quarterback John Elway, the pain from this one won't go away quickly. He will have arthroscopic surgery on his left knee later this week to repair cartilage damage he apparently suffered early in the fourth quarter. He also played with a pulled groin muscle, incurred in the third quarter. Elway is expected to be recovered from the surgery in about three weeks.

"Elway didn't seem as mobile in the second half," said free safety Eric Williams, whose interception at the end of the game set up Pittsburgh's winning touchdown. Elway, who completed 19 of 37 passes for 184 yards, was only eight of 17 for 79 yards in the second half.

The Steelers stopped the Broncos' offense regularly, when it didn't stop itself with two interceptions of passes by Malone.

The Broncos gained all but 51 of their yards through the air. But, were it not for a 52-yard halfback pass in the second quarter, Denver's longest reception would have been nine yards.

"We had a lot of pressure on Elway, but played off the receivers in the secondary," Williams said.

"Let them go underneath," he said. "Just don't let them go for the big play."

On offense, the Steelers no longer have Franco Harris and Rocky Bleier, but Pollard and Abercrombie, old Baylor teammates who combined for 1,461 yards this season, totaled 174 yesterday.

Denver had not allowed an opponent to gain 100 rushing yards in five straight games before Pittsburgh's 169 net yards, counting Malone's lost yardage. Only Chicago, with 302 yards, and New England, with 195, outperformed the Steelers in matchups with Denver.

"The Western Division teams all throw the ball a lot," Pittsburgh Coach Chuck Noll, "and they're not used to seeing much running."

Pollard, who gained 99 yards on 16 carries, said the Steelers' lightly regarded offensive line made his job surprisingly easy.

"I knew we could handle them up front," he said. "Those were the most consistently big holes I've ever run through. We've got a young offensive line and, earlier in the season, they were making a lot of mistakes that were stopping our drives; a lot of penalties. But not today."

Nose tackle Gary Dunn, who had the other interception, said this has been "an up-and-down season" for the Steelers. Right now, they're up; Pittsburgh has won three in a row to improve its record to 10-7.

This team won its biggest games on the road: against San Francisco (20-17), the Los Angeles Raiders (9-7) and, now, Denver.

"We play our best on the road," Williams said. (The Steelers' road record this season was 3-5, but who's counting?)

"We play our best when we aren't supposed to."