KANSAS CITY, Mo. -- Danny Valencia's own grandchildren may have trouble believing this story one day.
Not only was his first major league home run a grand slam, it came in a 19-1 victory. And on a night he went 4 for 4. And, topper of toppers, it was off the reigning American League Cy Young winner in a six-run first inning.
The rookie third baseman, who didn't even homer in the minors this year before being called up in early June, cleared the bases against Zack Greinke in the first inning of Minnesota's rout of Kansas City on Monday night.
"What better way to start it off?" Valencia said with a big grin. "Not just hit a home run, but a grand slam, and off a guy who's an accomplished big leaguer and won the Cy Young. It was great."
Valencia didn't know he'd gone into the record book as the first Minnesota Twin to hit a grand slam for his first major league homer.
"Really? That's awesome," he said. "Pretty cool."
Joe Mauer did even better on a night the Twins set a season high for runs and tied their season best with 20 hits. The AL's 2009 MVP was 5 for 5 with a home run and a career-high seven RBIs.
"It was just one of those nights where everything we swung at started finding holes and going all over the place," said Twins manager Ron Gardenhire. "A great night offensively for us. A lot of people involved all the way up and down. You don't see that too many times."
Mauer had three singles, a double and a three-run home run that made it 17-0 in the seventh. The five hits tied his career best. The crowd booed in the eighth when Drew Butera pinch hit for him.
"I asked him if he wanted another bat," said Gardenhire. "Do you want to hit? He said, 'No, I'm good.' That's good enough for me."
The Twins skipper is planning to give his All-Star catcher as much rest as possible the second half of the season.
"A big catcher like he is, a guy who's on the bases a little more than most other catchers, if we can do that, we're going to do that the best we can and hopefully get him through some of the aches and pains that catchers go through this time of year," Gardenhire said.
Five Twins had multihit games. Their 11 extra-base hits included two home runs, two triples and seven doubles. Alexi Casilla had three RBIs and scored three runs and Delmon Young had four hits, an RBI and two runs scored.
Virtually unnoticed among the offensive fireworks was the best game Francisco Liriano (9-7) has thrown all year. The Twins starter threw seven shutout innings, allowing just three hits, with no walks and six strikeouts.
Greinke (6-10), who has been bothered by a sore shoulder, got roughed up for eight hits and eight runs in just four innings, one of the worst outings of his career, and dropped to 0-3 against Minnesota this year.
Valencia, a rookie third baseman, also scored four runs. His grand slam capped a six-run first inning against the reigning Cy Young winner.
"You shouldn't have a game like this ever," said Greinke. "It was just that bad. It was just a bad game. It was a bad everything. It was just bad the whole time. My fastball was really bad. My off-speed was OK, but every fastball was hit hard. Every time I threw it in the strike zone, they hit it hard."
Needing a triple for the cycle in his last at-bat in the eighth, Valencia walked on a 3-2 pitch from Dustin Hughes, the fifth Kansas City pitcher.
"First home run a grand slam off Greinke, that's something to write on the ball," said Gardenhire. "That young man's as good as they get as far as pitchers go."
In a prelude of what the night would hold, the Twins came within a couple of inches of becoming just the fifth team since 1974 to have its first four batters combine for the cycle.
Jason Repko led off the game with a double, then trotted home when Casilla tripled into right-center. After Mauer singled, Young launched a Greinke fastball into deep left field. The ball was only a few inches short of clearing the fence, and Young settled for an RBI double.
Kansas City's Jason Kendall became the fifth catcher in major catcher in major league history to catch 2,000 games. The 36-year-old is in his 15th season.
It was the fourth time Mauer had five hits, and the second against Kansas City this year. ... Royals RHP Gil Meche gave up seven runs on eight hits in four innings Monday in a rehab assignment at Triple-A Omaha against New Orleans. ... KC SS Yuniesky Betancourt was a late scratch because of a "personal emergency."