PITTSBURGH - For a so-called meaningless game that allows them to rest their stars and heal their injuries before the playoffs, the Pittsburgh Steelers are taking it very seriously.Seriously as in Cleveland Browns serious.Seriously as in this team can't afford to lose again serious.That's what losing will do to a team that hadn't lost in two months until last week. And what not wanting to lose to the Browns for a third consecutive season will do to a team embarrassed by losses to them the previous two seasons.The Steelers (12-3) would seem to have little to gain by beating Cleveland on Sunday and denying the Browns (7-8) their first .500 season since their return to the NFL in 1999.The Steelers have locked up a first-round bye and home-field advantage throughout the AFC playoffs, and the Browns can't make the postseason even if they win.But, just as there are no Bears-Packers or Giants-Eagles games that are truly meaningless, regardless of the standings, Browns-Steelers games don't fit snugly into that category, either.What the Steelers don't want to lose is the confidence and momentum they built, slowly yet relentlessly, while winning 12 of 13 games. Or the edge they developed before an unexpected 26-23 overtime defeat at Cincinnati last Sunday ended a seven-game winning streak, the NFL's longest this season.Lose to the Browns, even in a game in which their starters might not play past halftime, and the Steelers would look eminently beatable to whichever team they play Jan. 19 or 20 in the playoffs, and they know it."What happened last week, I'm glad we got it out now," linebacker Joey Porter said. "We definitely want to hit the playoffs on a high note. To lose two in a row would devastate us right now."That's why Jerome Bettis, who has missed four games with a groin injury, might get some carries so he doesn't go into the playoffs off a six-week layoff. Why Kordell Stewart, the Steelers' MVP during what could be the second-best regular season in franchise history, might play more than just a series or two."As long as we keep winning, that's all that matters," Stewart said.That's why Hines Ward will be looking over his shoulder, and not just for the ball. He was fined $5,000 for standing over defensive back Earl Little after leveling him with a hit during Pittsburgh's 15-12 overtime victory in Cleveland on Nov. 11, a play that infuriated the Browns."I know I'm going to be a marked man," said Ward, who later apologized for taunting an injured player. "They would love nothing more than to put me out and make me miss a playoff game. I know Earl and a couple of other guys want some get-back at me."Little wouldn't mind putting a big hit on Ward, but said, "I'm not going to try to intentionally hurt the guy."The Browns aren't taking the game lightly, either.Of the Browns' five wins in 1999 and 2000, two were against Pittsburgh; now, the Browns could finish off by far their best season since their return by going 8-8."This week is our first chance at a .500 season since the franchise came back in 1999, so this is a huge game for us," said quarterback Tim Couch, who had the remaining four years of his contract picked up by the team Friday and picked up an $8.7 million bonus.Should the Steelers win, a 13-3 record would be their best in coach Bill Cowher's 10 seasons, and the franchise's best since the 1978 Super Bowl champions went 14-2. There might be a lesson here, too; the 1994 Steelers also could have finished 13-3, but they lost an essentially meaningless 37-34 decision at San Diego in their regular-season finale.That started a string of four consecutive losses in nonessential end-of-season games under Cowher from 1994-97, all on the road. But Sunday's game is at Heinz Field, where the Steelers are 6-1 in their first season there."The biggest thing you're playing for is to have that crowd, that energy, that little edge," said Cowher, rankled earlier in the week when Browns coach Butch Davis referred to him by his last name.Even if this Browns-Steelers game once would have had a lot more of all the above. The game, originally scheduled for Sept. 16, was to have been the Steelers' first home game in Heinz Field. It was postponed by the terrorist attacks, costing those fans who paid big money to buy seats from scalpers for what they thought would be the home-field opener.Instead, it became a meaningless game _ except to those who will play in it."We have the opportunity of a lifetime here," Stewart said, reflecting on what the Steelers could do in the playoffs. "We've just got to keep this going."