The San Francisco 49ers won their 2019 regular-season opener. That has to feel good, right? The team is happy to be headed into Week 1 with a 1-0 record, but it was the defense that starred during Sunday's outing. The unit carried the team to the 31-17 victory over the Tampa Bay Buccaneers.

The offense ... well, it struggled. It struggled to get into a rhythm, and it struggled to be as productive as most hoped it to be this season. The players on that offense know there is still work to be done and hope for a better outing against the Cincinnati Bengals.

"There's a lot of things to work on, definitely," tight end George Kittle told reporters on Thursday. "Three touchdowns called back on penalties. You can't do that if you want to win. We got bailed out by our defense, I think. I think everyone said that.

"We're just going to try to focus on the little things because I think that's what we missed out on, a lot of little things, whether it's alignments, some holding calls. If we can just clean those up, I think that we're a very dangerous team."

Tackle Joe Staley was equally disappointed in the offense's Week 1 performance.

"As an offense, last week, we felt we weren't the reason we won that game," Staley said. "Our defense obviously played really well. We were pretty disappointed in the way we played offensively. We left a lot of points out there on the field. We had a couple of unfortunate penalties at inopportune times. It took away a couple of touchdowns for us.

"As far as in our O-line room, up front, did some good things, especially in pass protection, but our run game wasn't there."

As for Jimmy Garoppolo, Kittle believes his quarterback is confident in the pocket and how he delivers the football to his targets.

"He's looked good all week," Kittle said of Garoppolo. "We're looking forward to it. We've got red-zone (drills) tomorrow, and get it [clicking] a little bit more there, and score some more touchdowns."

Kittle added that the goal is to win all their games this season. That's what the 49ers are focused on moving forward.

"Most NFL teams don't win 16 games," Kittle said. "We're going to do our best to try to do that. That's our goal. We're just going to try to win them all."

The nice thing is that, despite some obvious struggles, the players never lost confidence on the sideline against the Buccaneers, even later in the game.

"There was no panic on the sideline," Staley said. "Our defense was rolling, feeling really good. Offensively, we were just kind of talking. We got the ball back with about five minutes left, obviously, at the end of the game right there.

"We were saying, 'Just one more drive.' We didn't care what we'd done so far. We just needed one more drive, get some first downs, get the ball moving. We were able to do that, and get some points on the board, get a field goal.

"I think that's one of the reasons we won. There was no panic, our defense was playing incredibly well, and we were playing team football."