It was a rough trip to Buffalo for Lamar Jackson.

The star Ravens quarterback had a controversial interaction with a Bills fan — and then his team collapsed in a heartbreaking 41-40 loss Sunday night.

Baltimore was celebrating after a one-handed DeAndre Hopkins touchdown catch gave the Ravens a 34-19 lead near the end of the third quarter when a Bills fan slapped both the veteran receiver and Jackson in the helmet as they ran alongside the stands.

Jackson responded by shoving the fan, who was ejected from the game.

“He slapped me, and he was talking — so, I just forgot where I was for a little bit,” Jackson said after the thriller. “You have to think in those situations. You have security out there; let security handle it. But I just let my emotions get the best of me. Hopefully, it doesn’t happen again. I learned from that.”

Jackson said, though, he won’t shy away from similar celebrations going forward.

“I’ve never seen our fans do that,” Jackson said. “So, I’ll probably do it again when we score a touchdown. It’s not nothing against the fans. I’m just celebrating when my teammates get a touchdown.”

The fiery moment seemed to be a blip on the Ravens’ evening as they were positioned to open the season with a statement win over the Bills, who eliminated Baltimore in the Divisional Round of the playoffs a season ago.

But Josh Allen led the Bills to a stunning comeback, scoring two touchdowns and a field goal in the final four minutes to erase a 15-point deficit.

A crucial Derrick Henry fumble aided the comeback after the Bills had cut the lead to 40-32.

“You just got to finish the game,” Jackson told reporters. “It’s not over until there is zero, zero, zero on the clock. And we found that out tonight.”

Jackson finished the game with 209 yards passing, 70 rushing and three total touchdowns.

The Ravens host the Browns in Week 2.