Cedric Mullins had two home runs and singled in another run for a total of five RBIs as the Baltimore Orioles routed the Toronto Blue Jays 12-2 on Thursday in Major League Baseball's opening day.

Zach Eflin (1-0) gave up two runs on two hits and a walk, striking out two over six innings of work. Relievers Seranthony Dominguez, Keegan Akin and Bryan Baker combined for three scoreless innings.

Andres Gimenez's two-run homer in the fourth inning was the first hit Eflin gave up to Toronto (0-1). Gimenez drove in Vladimir Guerrero Jr. with the blast.

Jose Berrios (0-1) laboured through five innings of work, giving up six runs on nine hits and two walks but striking out five.

Richard Lovelady, Jacob Barnes, Chad Green, Yariel Rodriguez and Nick Sandlin came out of the Blue Jays' bullpen, giving up six runs over four innings.

Scattered boos during U.S. anthem

Some Blue Jays fans booed the United States' national anthem.

There were scattered but audible boos from the sold-out crowd at Rogers Centre as the "The Star-Spangled Banner" was sung by the 40-person ensemble from the local stage production of the Lion King.

Those jeers turned to cheers and singing as the crowd joined in with the musical's cast for "O Canada" as members of the Canadian armed forces unfurled a giant Canadian flag in the outfield.

Blue Jays manager John Schneider, who is from Princeton, N.J., said that he had spoken to his players about the possibility of the anthem being booed.

"That's not our focus," said Schneider during a pre-game conference with reporters. "Unless it's like [country music star] Chris Stapleton singing the anthem, I'm not really looking forward to the anthem unless he's singing it.

"We're expecting whatever is going to happen, and then focusing on the game. It's unfortunate. We get it, but I think we're focusing on the game."

Orioles manager Brandon Hyde also said his team had prepared for the possible boos.

"We've communicated that with our players, and everybody understands," he said in his pre-game scrum in the visitors' dugout. "We understand all that.

Hall of Famer Rickey Henderson, who was on the Blue Jays' World Series-winning team in 1993, was honoured with a moment of silence before the national anthems.

A message was played over the ballpark's public address system before the anthems, encouraging fans to be respectful as baseball has historically been a refuge from political turmoil.

It's not the first time fans at Rogers Centre have booed the U.S. anthem.

There were loud jeers when the downtown ballpark hosted "Elimination Chamber," a premium live event promoted by World Wrestling Entertainment on March 1.