CHARLOTTE, N.C. -- Good thing Carolina Panthers quarterback Cam Newton has a strong defense to give him time to adjust to his evolving offense.

The 2015 NFL MVP continued to show signs of rust in Sunday’s home opener against Buffalo as he comes back from offseason shoulder surgery.

For the second straight week, Newton missed several wide-open receivers on key plays. None was bigger than a third-and-goal pass from the 2 to rookie running back Christian McCaffrey, who, despite his amazing athletic ability, couldn’t get high enough to haul in the pass late in the fourth quarter.

But the Panthers (2-0) survived for a 9-3 win primarily because of a defense that has allowed only two field goals in the first two games.

They survived because of a smothering run defense that allowed only 51 yards in the opener at San Francisco and 69 against the Bills.

They survived despite the ineptitude of the offense, which continued to shoot itself in the foot with missed opportunities.

"We just have to score,'' Newton said after the Panthers dominated the clock 38:53 to 21:07. "Any time you control the ball for that long you know you're doing something right. We just have to find ways to just put the ball in the last rectangle on the football field. It wasn't like we were stagnant on offense.''

But Newton did struggle at times, in part because Bills coach Sean McDermott frustrated him with the kind of pressure with which he had frustrated Panthers opponents during the past six seasons as the team’s defensive coordinator.

"These were self-inflicted frustration things,'' Newton said. "Sean McDermott has an unbelievable defense -- very stout up front. But at the end of the day there was nothing we weren't prepared for. Through it all I have to be better and I will be better and I will. That's where the frustration lies in myself.''

But don’t ever question Newton's mental or physical toughness. He limped off the field early in the fourth quarter with an ankle injury after being sacked for the sixth time. He spent several minutes being evaluated under a portable sideline tent.

When he emerged, the Panthers were holding on to a 6-3 lead in a game they had dominated.

"Man, it was scary,'' said Newton, who had ankle surgery prior to the 2014 season.

Newton, despite the frustrations that were becoming obvious with his body language, led the Panthers to the 2-yard line before having to settle on another field goal after missing the wide-open McCaffrey on the right side with nothing but air between him and the goal line. He also missed tight end Ed Dickson earlier for what could have been a huge gain and first down.

"Missing layups like that, it's uncalled for,'' Newton said. "I wish I had two or three balls back, but that is every single game.''

ESPN analyst Bill Polian, the former general manager of the Panthers and Bills, called this one right when he said McDermott knew how to frustrate Newton.

It didn’t look that way early, as Newton & Co. moved up and down the field. They held a 193-to-39 edge in total yards in the first half and owned a four-to-one edge in time of possession.

But the Panthers wound up with field goals instead of touchdowns, and the pressure eventually started to get to them. They were bailed out by a defense that new coordinator Steve Wilks says has a chance to be the best in the league. Were it not for quarterback Tyrod Taylor scrambling for 55 yards, the Buffalo running game would have been nonexistent.

That’s a good thing for the Panthers as they continue to work out the wrinkles in an offense that is supposed to depend more on weapons like McCaffrey and less on the quarterback to run.

Even then, the Panthers needed a bit of luck, which they got Sunday as Buffalo wide receiver Zay Jones dropped a pass at the Carolina 2 with nine seconds left. But coach Ron Rivera and company will take luck after losing six games last season by three points or less.

"I think it shows we don't have to play at our best to win'' Rivera said. "We played hard. That's one thing. We didn't play as smart as we need to at times. But as I said, give these guys credit. This is going to be a good football team. People better not sleep on them.''