PITTSBURGH -- The Pittsburgh Steelers put up big offensive numbers but that is not why they were excited about their first win of the season.

Quarterback Ben Roethlisberger threw for 369 yards and three touchdowns, wide receiver Antonio Brown had 195 receiving yards and running back DeAngelo Williams tied a franchise record with three touchdown runs as the Steelers built a 26-point halftime lead and rolled to a 43-18 victory over the San Francisco 49ers on Sunday.

Though the Steelers finished with 454 total yards after racking up 464 in its season-opening loss to the New England Patriots, it was the play of the young defense that made the victory satisfying for them. Pittsburgh held the 49ers out of the end zone until the fourth quarter, when the game was out of reach, and also stopped San Francisco (1-1) on downs twice inside the 5-yard line in the second half.

The 49ers converted only one of four red-zone opportunities after the Patriots scored touchdowns on all four red-zone chances.

"We didn't do as well as we would have liked a week ago and we responded accordingly," Steelers coach Mike Tomlin said. "We met this week's challenges. We weren't perfect. We gave up some big plays, particularly in the second half, but we'll take the win."

Roethlisberger completed 21 of 27 passes and Brown had nine receptions, his last going for a 7-yard touchdown with 7:43 left to close the scoring. Brown became the fourth player in Steelers' history with 400 career receptions, joining Hines Ward, Heath Miller and John Stallworth.

Williams rushed for 77 yards on 20 carries and scored on runs of 2, 2 and 1 yards as he again filled in for Pro Bowl running back LeVeon Bell, who served the second game of a two-game suspension for violating the NFLs' code of conduct. Williams had 127 yards in the opener after signing as a free agent in the offseason following nine seasons with the Carolina Panthers.

"I said before I got here, this team right here is a Super Bowl contending team," Williams said "That's why I wanted to sign here. We showed that today."

The Steelers scored touchdowns on their last four possessions of the first half to take a commanding 29-3 lead in dropping the 49ers to 1-1 and improving to 13-2 in home openers, including 8-1 under Tomlin.

49ers running back Carlos Hyde left the game in the third quarter with a head injury and did not return after rushing for 43 yards on 14 carries. Coach Jim Tomsula said Hyde was cleared to return to action but he opted to hold him out.

Hyde led all NFL rushers in Week 1 with 168 yards in a victory over the Minnesota Vikings in the second-year pro's first career start.

49ers quarterback Colin Kaepernick was 33-of-46 passing for 336 yards and two touchdowns and rushed for a team-high 52 yards on eight carries. The scoring passes covered 14 yards to wide receiver Anquan Boldin and 71 yards to wideout Torrey Smith.

The touchdown reception was a career long for Smith, who had six catches for 120 yards.

"I thought they fought through the game," Tomsula, the first-year coach, said of his players. "Offensively, I thought we really kept fighting back and not blinking. We didn't get it done. That's the bottom line."

Steelers linebacker Jarvis Jones said communication was the key to stopping the 49ers.

"This game is played above the shoulders," Jones said. "Everything we are doing out there is so we can all get on the same page. It's very critical."

Roethlisberger opened the scoring with a 2-yard pass to Miller, the veteran tight end, with 4:20 left in the first quarter, then threw a two-point conversion pass to Brown.

The 49ers countered with Phil Dawson's 47-yard field goal to cut the lead to 8-3 with 10:27 to go in the second quarter.

The Steelers then answered with a pair of touchdown runs by Williams sandwiched around a 35-yard scoring pass from Roethlisberger to wide receiver Darrius Heyward-Bay to make it 29-3. Williams added his third score in the fourth quarter.

The new-look 49ers defensive, following the retirements of linebackers Patrick Willis and Chris Borland, and the release of end Aldon Smith, seemed overwhelmed.

"We're taking a loss and we're a young team," San Francisco linebacker NaVorro Bowman said. "How we respond is going to be the great challenge for us."

NOTES: Steelers LB Ryan Shazier (shoulder), who had a team-high 15 tackles -- including three for loss, one sack -- left the game in the fourth quarter but coach Mike Tomlin said the injury did not appear to be serious. ... Steelers QB Ben Roethlisberger improved his regular-season record to 107-53, tying Terry Bradshaw's franchise record for wins by a quarterback. ... Steelers WR Antonio Brown extended his NFL record to 34 consecutive games with at least five receptions and 50 yards. Since the streak started to open the 2013 season, Brown leads the league with 369 targets, 257 receptions and 3,525 receiving yards. ... 49ers backup TE Vance McDonald (knee) left the game in the second quarter and will be evaluated Monday. ... 49ers RB Reggie Bush (calf) and WR Bruce Ellington (ankle) were inactive along with Steelers CB Cortez Allen (knee) and QB Landry Jones (concussion).