Hosmer tied the game at 1 after placing a 90-mph cutter 389 feet into left field, and Perez followed up two at-bats later by driving a 93-mph fastball over the fence for a two-run homer to give the AL a 3-1 lead at Petco Park.
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"Oh man, it was unbelievable," Hosmer said in an in-game interview on FOX. "We couldn't even get an interview in before Salvy came back and turned around and did that. This whole week, this whole San Diego All-Star Game has been unbelievable. It's a dream come true, and it kind of felt like my first big league homer right there. It was special."
Hosmer and Perez are only the fifth and sixth Royals to homer in the All-Star Game, and Hosmer's was their first since Bo Jackson's mammoth homer in the 1989 All-Star Game. The other Royals to homer in an All-Star Game are Cookie Rojas (1972), George Brett (1984) and Frank White (1986).
"I told Hoz they made me feel like a proud papa," said manager Ned Yost on FOX. "Two homers by Hoz and Salvy was really, really fun to watch."
Hosmer's homer came in the first All-Star Game at-bat of his career, while Perez's power display comes with no surprise, given his career-best .217 ISO through his first 78 games this season.
Hosmer and Perez became the eighth pair of teammates to homer in the same All-Star Game and only the second to do it in the same inning. Dodgers Steve Garvey and Jimmy Wynn hit back-to-back homers in the second inning of the 1975 All-Star Game.
According to ESPN Stats & Info, a player has homered off a former teammate from the previous year just three times in the All-Star Game, and two of them (Hosmer/Perez vs. Cueto) happened on Tuesday. The only other one was Alfonso Soriano (Rangers) off Roger Clemens (Astros) in 2004.
Carlos Collazo is a reporter for MLB.com based in San Diego. Follow him on Twitter @CarlosACollazo. This story was not subject to the approval of Major League Baseball or its clubs.