PITTSBURGH -- For the second week in a row, the Pittsburgh Steelers' first-unit offense failed to put any points on the board as the team dropped Saturday night's preseason game to the Buffalo Bills 9-3.

This time, though, Russell Wilson -- making his preseason debut -- led the unit to its scoreless outing in five series, while Justin Fields' unit mustered only a field goal in five series of its own.

Wilson, 35, completed 8 of 10 attempts for 47 yards over five series. But the starting offensive line gave up three sacks in the first three series for a loss of 21 yards, and the unit picked up only one first down while averaging a paltry 1.6 yards per play.

"We didn't do a good enough job of protecting the quarterback," coach Mike Tomlin said. "We've got to do a better job in pass protection than we did -- not only in possession downs but just in general. I was really up-front with the group about it in that regard, that can't be a problem for us."

Playing right tackle, former first-round pick Broderick Jones gave up two of the sacks on Saturday night. Rookie right tackle Troy Fautanu, who sustained a knee injury in the previous game, didn't play against the Bills. Jones declined interview requests after the game.

Because the Steelers failed to sustain drives with Wilson at quarterback, Tomlin said it was difficult to evaluate the veteran's performance.

"It's somewhat of an incomplete study because you just don't get a chance to see them operate or us operate or us establish rhythm and personality when you're not winning possession downs," Tomlin said.

Wilson's best throw of the day came on third-and-2 during his final series when he hit Van Jefferson over the middle for an 11-yard gain. That drive, though, stalled out a couple of plays later, and kicker Chris Boswell missed a 52-yard field goal.

"I was trying to play in rhythm, trying to get the ball out when we could and then also just trying to hang in there on the third down," Wilson said, evaluating his performance in the pocket.

Wilson, who injured his calf on the eve of training camp, said he felt "great" during the game.

"I felt strong," Wilson said. "I wasn't thinking about [my calf]. Anytime you have an injury, sometimes if you're worried about it, you're in the back of your mind. You're thinking about it. Didn't feel that at all really the past week or so. And I felt really good this past week and everything else. And so to play out there tonight just to get back out there in the black and gold was really cool."

Prior to Saturday night's game, Tomlin told the Steelers' website that the competition between Fields and Wilson would heat up now that Wilson is back from his calf injury. When asked after the game what he needed to do to win the competition, Wilson expressed confidence in his abilities.

"I think the best thing that I can do, personally, is just stay consistent in an approach," Wilson said. "Had a little bump in the road with my calf. But the best part is I was out there tonight and playing. ... And I know what I can do when I'm a hundred percent, I'm getting close."

Once Wilson exited following his fifth series, Fields took over and finished the game. Though Fields led the second unit to just three points prior to halftime, his group racked up 160 yards of offense and averaged 4.1 yards per play. Fields' legs were a difference-maker as the quarterback extended plays and picked up yards with his feet.

Not only did Fields lead the team with 92 passing yards on 11 of 17 attempts, but he also led the Steelers with 42 rushing yards on eight carries -- including a 20-yard scamper in a two-minute drill.

"I'm just playing football out there," Fields said. "At the end of the day, if I got to run a little bit more, then that's what I have to do. But I don't go into games saying that, 'Oh, I'm going to have to run a lot more or show off my legs more.' I'm just reacting and playing football."

The Steelers' longest throw of the night came as Fields escaped what looked like a sure-thing sack, rolling out to his left and finding wide receiver Dez Fitzpatrick on the sideline for a 19-yard completion in a scramble drill.

"Sky's the limit with that guy," Fitzpatrick said. "Whenever the ball's in his hands, you have a chance for explosive play. That's why us receivers just always have to stay open. Never think that the play is over with. Even if you think it's a sack or anything, he will shed it, use his legs, 40-yard run or shed it. And it's exactly with the play with me, find a receiver downfield."