CHICAGO - Home runs ruled the day as the batter's boxes turned into launching pads on Tuesday night in Chicago. Unfortunately for the Royals, they didn't come up with enough of them and/or they didn't have enough people on base when they hit the ball out of the park.

The Royals and White Sox scored 10 runs, and each came via the long ball. However, the Royals were on the short end of the stick as they dropped the series opener 7-3 in front of an announced 15,196 people plus 1,236 dogs on "Bark at the Park" night at Guaranteed Rate Field.

Each team hit three homers, but the White Sox' first one did a lot of damage and forced the Royals (53-92) to play catch-up for most of the game thanks to a first-inning grand slam.

Royals starter Jakob Junis allowed five earned runs on six hits (two homers), three walks and seven strikeouts in five innings. He pitched into the sixth and faced two batters but did not record an out before giving way to the bullpen.

"We were hitting the ball out of the ballpark, too," Royals manager Ned Yost said. "We just didn't have guys on like they had guys on. Jake did a good job of holding the fort there. He did a good job limiting the damage after that."

Adalberto Mondesi, Alex Gordon and Ryan O'Hearn each hit home runs in the loss, while Whit Merrifield and Gordon had two hits apiece.

Mondesi started the scoring with a solo home run, his eighth of the season and first since July 2, on a 2-0 pitch he mashed 429 feet to center field.

Mondesi, who returned to the lineup on Sept. 1 after a lengthy stint on the injured list, showed in his first game back that he can have a major impact with the combination of his speed and bat. He collected four hits and three steals in his return. But he's not by any means a slap hitter.

"Just got a good a good pitch to hit, easy swing and good results," Mondesi said of the home run.

In the bottom half of the inning, the White Sox (64-80) sandwiched a pair of singles around a walk to load the bases. Then Eloy Jimenez went down and got a sinking fastball at the bottom of the strike zone and blasted the first grand slam of his career to give the White Sox a 4-1 lead with Junis having recorded just one out in the game.

"Some (pitches were off the mark). Some bad luck," Junis said of the first inning. "I threw a changeup that came back and hit me in the wrist. I let that go it might be a double play. Could've been out of the inning.

"Then Jimenez, I threw a sinker down and in that was a pretty good pitch and he just sliced it the opposite way for a homer. Once you give up four in the first, it's hard to come back from that."

Back-to-back solo home runs by Gordon and O'Hearn in the second inning - the fifth time the Royals have gone back-to-back this season - made it a one-run game, 4-3, but the White Sox answered when Adam Engel led off the second with a solo bomb to make it 5-3.

White Sox third baseman and cleanup hitter Yoan Moncada hit a two-run home run against relief pitcher Kevin McCarthy in the bottom of the seventh to increase his club's lead to 7-3. Moncada's mammoth blast went 452 feet to straightaway center field.

The Royals scored all three of their runs of White Sox starter Ivan Nova in the first 5 2/3 innings. However, the bullpen quartet of Jace Fry, Evan Marshall, Aaron Bummer and Jimmy Cordero held the Royals scoreless for the final 3 1/3 innings.

The teams continue their three-game series on Wednesday night.