Right before Game 3 of the ALDS between the Blue Jays and Yankees, Yankee Stadium echoed with boos during “O Canada.” Now, it turns out, that wasn’t an isolated moment. Reportedly, anthem booing has been pretty common across North American arenas lately.

But now, it’s starting to feel like a signature part of the Yankees–Blue Jays rivalry. During Game 4, it happened again. Despite New York’s creative attempt to prevent it, the Canadian national anthem was once more met with boos from the crowd.

“Yankees game ops attempted to dissuade from the heavy booing during O Canada by showing Don Mattingly on the screen. Changed to claps for a few seconds, then right back to the boos,” MLB insider Mitch Bannon reported.

Remember Don Mattingly?

Back in Game 2 of the 1995 ALDS, he crushed a game-winning homer off Andy Benes. That was a huge moment that marked the Yankees’ first playoff run in 14 years and his only postseason as a player. But funny enough, Mattingly’s now on the other side.

He’s working as the Blue Jays’ bench coach under John Schneider.

But the Yankees’ game ops team actually tried to use that connection to preserve respect. Before Game 4, they showed Mattingly on the big screen during the Canadian national anthem, hoping his familiar face might calm the Yankee crowd. While fans cheered for a few seconds there, the booing resurfaced soon.

Much like the intense on-field battles between these two teams this season, this new anthem drama seems to be the latest twist in their growing rivalry. And with both squads locked in since the start of the postseason, we probably haven’t seen the last of it.

The Yankees and Blue Jays are in a battle

The Yankees-Blue Jays rivalry is no longer getting battled within the foul line. Rather, it is getting hotter off-field, too.

Last month, reports surfaced that Canadian residents were blocked from buying tickets to the Blue Jays’ ALDS games at Yankee Stadium. And now, the stands are almost entirely dominated by fans in pinstripes, creating a loud, one-sided home atmosphere.

According to multiple reports, anyone trying to grab tickets for Game 3 or a potential Game 4 on Ticketmaster was met with a notice. It says sales were “restricted to residents of New York, New Jersey, Connecticut, and Pennsylvania.”

And guess what, the Blue Jays also have their own version of that policy.

They started restricting Rogers Centre ticket sales to buyers with Canadian billing addresses, and kept that rule in place throughout the playoffs. The goal is the same: To protect their home-field advantage and keep visiting fans from taking over the stands.

These ticket restrictions have become another symbol of how fierce the Yankees–Blue Jays rivalry has grown. Add in the recent anthem-booing incidents, and it’s starting to feel like this rivalry extends far beyond the field.