SAN DIEGO -- The bases were loaded for Lorenzo Cain in the eighth inning. Trying not to do too much, he found a flair for the dramatic in the Kansas City Royals' 12-6 win over the San Diego Padres on Saturday afternoon.

"I was looking for a pitch to drive and get into the outfield, that was the main goal," Cain said. "It was a two-seamer inside. I pulled my hands inside and it got out for me. It was huge."

Cain's grand slam was among his two home runs and led to five RBIs as Kansas City evened the series. The Royals had five home runs, their most since July 23, 2003, at the Minnesota Twins.

Salvador Perez hit the go-ahead homer in the eighth inning, right after Eric Hosmer's two-run tying blast, as Kansas City scored nine runs in the inning. Cain's second career grand slam, off reliever Jose Valdez, was the first of the year for the Royals and his third hit of the game.

Perez's 100th career homer was his third in three straight games in San Diego, including last summer's All-Star Game. Hosmer, who was the All-Star Game MVP and had a big homer here in March during the World Baseball Classic for the USA, added his sixth homer of the season.

"It's a fun place to play," said Hosmer, who homered in the same inning as Perez, just like they did in the All-Star Game. "The weather here doesn't get any better, it's a beautiful field and a great atmosphere. I've had some great moments and I don't really know what the cause of it is."

The Perez and Hosmer homers came against Brad Hand (1-4), the Padres' fourth reliever.

Travis Wood (1-2) got the win.

Jose Pirela had a homer and three RBIs for San Diego, finishing a triple shy of the cycle. Pirela and Cory Spangenberg had three hits.

The Padres used six relievers after Miguel Diaz's starting debut fizzled. Diaz lasted two-plus innings, allowing a hit and three walks with a strikeout.

"Probably a little bit over-amped starting for the first time," Padres manager Andy Green said. "The way he was coming out with guns blazing it was going to be hard to get into the fourth inning with him today."

Diaz said, "It was definitely a case of me being a little too quick with my delivery."

Kansas City right-hander Ian Kennedy ran his winless streak to 15 starts. He worked six innings and was charged with four runs and six hits. He walked two and struck out five.

"All in all, his command was much better than it has been," Royals manager Ned Yost said. "He got us through six innings and we needed it. Our bullpen is on fumes right now."

The Royals scored single runs in the sixth and seventh to pull within 4-3. Cain homered and Whit Merrifield had a run-scoring single.

San Diego forged ahead 4-1 with a three-run fifth inning. Pirela had a two-run double and Yangervis Solarte knocked him in with a sharp single.

The Royals tied the score at 1 in the fifth on Alcides Escobar's first homer.

Diaz struggled with his control and wasn't around long enough to fix it. He walked a runner in the second, then was bailed out by a double play. But in the third, Alex Gordon opened with a single and consecutive walks to Kennedy and Whit Merrifield ended Diaz's day.

The Royals were poised for a big inning but fell short.

Craig Stammen entered and was asked to maneuver around the heart of the Royals' lineup. He struck out Jorge Bonifacio and got Cain to hit into a double play, which was started by a nifty play by shortstop Erick Aybar.

The Padres struck quickly when Pirela scorched his second homer in the majors and his first since playing with the New York Yankees in 2015. The leadoff batter smacked Kennedy's 93 mph fastball 409 feet for a 1-0 lead.

NOTES: Royals LHP Danny Duffy (oblique) isn't with the club as he stayed in Kansas City to continue his rehabilitation. Duffy has begun to play catch. ... Padres 1B Wil Myers didn't start because of an illness. ... Padres RHP Jered Weaver could require another bullpen session before being sent out on a minor league rehab start. ... There is no timetable for RHP Trevor Cahill's first bullpen session as he rebounds from a sore shoulder. The San Diego right-hander has resumed throwing but not off a mound.