BALTIMORE -- Upon finding out Monday that he would be making his third career major league start, Boston Red Sox rookie infielder Marco Hernandez got a hitting tip from none other than David Ortiz.

Trust your hands and be aggressive, Big Papi said.

Now, after one mighty swing, Hernandez has reason to do both.

Hernandez belted his first career home run, a three-run shot in the eighth inning against hard-throwing Baltimore Orioles reliever Mychal Givens, to put away a 7-2 victory in the Memorial Day opener of a four-game series between the top two teams in the American League East.

"It was amazing," Hernandez said. "To hit my first home run, to pull on top of the ball for three runs, it's awesome, man. As soon as I touched first base, I saw the ball in the stands, and I said, 'Yeah, that's gone.'"

Hernandez's home run, which grazed the top of the wall in right-center field and bounced over, was one of three hit by the Red Sox. Ortiz returned to the lineup after a one-game absence because of a sore left foot and blasted his team-leading 14th homer and his third in his past three games. Jackie Bradley Jr. broke a 2-2 tie in the sixth inning with a solo shot off Orioles starter Tyler Wilson.

Shortstop Xander Bogaerts extended his hit streak to 23 games with the first of two doubles in the third inning.

But while the Red Sox demonstrated their usual power, they pushed the game's first run across with their typically aggressive baserunning -- and a little luck.

Mookie Betts dashed home from second base on Bogaerts' tapper in front of the mound, alertly recognizing that nobody covered home plate after Bogaerts was thrown out easily at first. Orioles manager Buck Showalter contended that the ball hit Bogaerts and should've been ruled foul, but the play wasn't reviewable.

"Maybe that's one of the fortunate breaks we get with replay," said manager John Farrell, who nevertheless credited Betts with never breaking stride on his way to the plate.

Hernandez never stopped to admire his first career home run, the most impressive moment yet for a versatile infielder (he played third base Monday) acquired from the Chicago Cubs as the player to be named in a 2014 trade for lefty Felix Doubront.

"I just got to go there and hit a fastball," Hernandez said. "When you're a fastball hitter, you can go ahead looking for breaking ball because if he throws you a fastball, you can react. I tried for the fastball early in the count. Be aggressive early in the count."

Just like Ortiz told him.