PITTSBURGH — Call it addition by omission.

As Steelers coach Mike Tomlin rattled off the status of injured players on Tuesday, three names were noticeably absent – Rashard Mendenhall, James Harrison and Troy Polamalu.

It wasn’t an oversight by Tomlin. It’s just that he doesn’t think three of his team’s most vital contributors are hurt anymore. Barring a setback, Tomlin expects all three to be in uniform on Sunday when the Steelers (1-2) host Philadelphia (3-1).

“I think that’s a safe assessment,” Tomlin said.

The unusually emphatic endorsement by the typically cautious Tomlin is perhaps the closest thing to a sure thing for the Steelers, who are looking to avoid their first ever 1-3 start since Tomlin took over in 2007. Under Tomlin, the Steelers have started every season 6-2. They already have two losses. Ripping off the next five to keep that streak alive will be daunting.

Having a couple of former Defensive Players of the Year back won’t hurt. Harrison hasn’t played at all this season while nursing a lingering left knee problem. Polamalu missed the last two games with a strained right calf, while Mendenhall is at the very end of a lengthy rehab after tearing the ACL in his right knee on New Years Day.

“When we have those guys, we’ll appreciate it,” Tomlin said. “When we don’t have them, we’ll remain steadfast in our goals and our objectives.”

Even if they haven’t been met through the season’s first month.

While the offense has been remarkably consistent under new coordinator Todd Haley, the defense has looked toothless in the second half in losses to Denver and Oakland. The Broncos and Raiders had the ball a combined eight times in the second half against the Steelers and ended up scoring on seven possessions.

Polamalu and Harrison’s presence won’t hurt, but there’s no guarantee they will be a cure-all for a team in danger of losing serious ground to AFC North front-runners Baltimore and Cincinnati, both 3-1. Yet, the Steelers have been one of the most resilient teams in the NFL under Tomlin. Pittsburgh is one of only three teams to avoid back-to-back losses since the beginning of the 2010 season.

“There’s no panic in here,” quarterback Ben Roethlisberger said. “It’s still a marathon, but we need to get a win.”

A couple of defensive stops might be enough to get the job done. Getting some pressure on the quarterback might help. The Steelers have just five sacks through three games, which would put them on pace for less than 30 over the course of a season. Chris Carter and Jason Worilds have done little in that department while filling in for Harrison, allowing teams to focus their attention on stopping LaMarr Woodley coming from the right edge.

Pittsburgh hardly made Oakland quarterback Carson Palmer break a sweat as he threw three touchdowns in a

34-31 comeback victory on Sept. 23. Palmer led the Raiders to scores on all four of their second-half possessions, and he hit four straight passes on the drive that set up Sebastian Janikowski’s game-winning field goal.

The defensive veterans rallied around longtime coordinator Dick LeBeau last week, brushing off criticism that the Steelers had become too predictable. Safety Ryan Clark pointed out opponents’ familiarity with Pittsburgh’s 3-4 scheme didn’t matter because the Steelers simply outworked the guys across from them on the line of scrimmage. It’s a point Polamalu reiterated on Monday.

“We are not going to change,” Polamalu said. “It’s about how we execute and win our one-on-one matchups. If we don’t, it has nothing to do with the scheme of things. It’s just that we are underperforming.”

There are few players in the league who work more tenaciously than Harrison, who underwent a full workout last Tuesday but was not on the field when the team practiced on Wednesday. His left knee has been bothering him since minicamp to the extent he underwent a minor procedure on Aug. 15. He anticipated being ready for the season opener, but a month later is still waiting to take the field.

Harrison joked on Monday he’s more concerned about a charity fashion show the team is putting on Friday than making a guess on whether he’ll be available. Still, the sight of Harrison and Polamalu on the field Monday was enough to pump up cornerback Ike Taylor.

“You’re talking about two defensive league MVPs,” Taylor said. “Enough said.”