NFL MVP Cam Newton didn't lead the Carolina Panthers to a touchdown in Thursday's preseason opener at Baltimore, but he cost them one.

The Panthers were penalized 5 yards when Newton ran onto the field in celebration after an interception, and that negated linebacker A.J. Klein's 94-yard return for a touchdown.

"I just got too excited," Newton told reporters. "I was hoping they would give a warning."

Asked if he said anything to Klein afterward, Newton said, "Next question."

Cam Newton completed 5-of-6 passes for 36 yards in his preseason debut on Thursday in Baltimore. Tommy Gilligan/USA TODAY Sports

"I don't want to have a discussion about something that I've learned from," Newton said. "You live and you learn. ... It happened. We all learned something as a team. We're moving forward."

Keeping coaches and players on the sideline is a point of emphasis for the NFL this season. Newton learned that the hard way.

"We were told about them," Panthers coach Ron Rivera said of penalties for players and coaches being on the field. "We met with the referees about them, and we still did them, so I'm disappointed with that."

Carolina was also penalized 15 yards when an assistant coach was on the field after being warmed.

"It's a lesson learned," Rivera said. "If you're going to do it, do it now."

It wasn't all bad for Newton. He completed his first five passes and led Carolina to an opening field goal. He finished 5-for-6 for 36 yards.

As for his penalty, backup Derek Anderson cleaned that up with a 10-yard touchdown pass to Devin Funchess.