KANSAS CITY, Mo. — Naturally, the Royals and their fans made sure to celebrate on the occasion of their first game at Kauffman Stadium since winning the World Series in Queens in November.

That included a montage of highlights on the video board from their World Series victories before they raised their championship flag in leftfield.

What made the scene unusual — unprecedented, actually — was that the Mets had to stand along the third base line watching it unfold, having had their lineup announced earlier and thus being stuck there.

Never before in baseball history had a World Series loser been forced to watch the winner raise a flag before its opener, because never before has there been a World Series rematch on Opening Day.

The Royals displayed class in showing a Mets highlight video before introducing the visitors. They also did not include in the Royals highlights the errant throw home by first baseman Lucas Duda that was pivotal to the Royals’ Game 5 clincher at Citi Field.

Royals fans have not forgotten, though. Duda was the only Met they cheered during the introductions.

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Speaking of his 2015 misfire, the man who scored on that play, Eric Hosmer, said before the game that the Mets likely would draw motivation from facing the Royals — just as the Royals would have if they had opened last season against the Giants, the team that beat them in 2014.

“We would definitely want to make a statement,” Hosmer said, “show them, hey, we’re not going anywhere, and we realize that if we want to get to where we want to go it’s through you guys. So you want to show them what you’ve got.”