Rodriguez's last shot came off Greg Holland, a two-run homer -- the 604th of his career and 21st of the season -- that landed in the fountains beyond the left-center-field wall.
He also belted a solo shot in the sixth inning off starter Sean O'Sullivan, one of three Yankees homers in that inning, and followed up with a two-run shot off Kanekoa Texeira on his way to a five-RBI performance.
"That's why he's been such a great player for a long time," said manager Joe Girardi. "He's been such a great talent for a long time. Nothing really ever surprises me."
The performance marked the 56th multihomer game of Rodriguez's career, but just his fourth three-homer game, having last achieved that feat on April 26, 2005, against the Angels. The homer barrage also put him over the 20-home run mark for the 15th consecutive season, becoming one of just five players to do that in history. Hank Aaron, Babe Ruth, Willie Mays and Barry Bonds are the other four.
"He was dead-on today, that was for sure," said Royals manager Ned Yost. "I don't know what was more amazing -- that ball to center or the ball to left field in the fountain [off O'Sullivan], but he got hold of both of them."
Rodriguez credited hitting coach Kevin Long with an assist for Saturday's theatrics, saying they have had good sessions lately working on a flaw.
"It was about clearing my hips," Rodriguez said. "It was nice to actually get some good work and carry it into the game. ... He thought my hips weren't coming through and basically trying to come through about 70 percent. He got them to 100 percent, and I think it really helped."
The Yankees, who also received solo homers from Jorge Posada and Curtis Granderson in the victory, weren't complaining about the breakthrough.
"We're always looking for things to make guys better, and that's why K-Long is so good at what he does," Girardi said. "He never rests. He's always looking at little things, and if a guy is a little off, he's able to spot it. He spotted something and he went to work on it today, and it paid off."
Phil Hughes turned in a solid effort, limiting Kansas City to three runs in six innings -- more than enough support for Hughes, who entered Saturday receiving 7.48 runs scored per nine innings, tops among Major Leaguers.
"Why can't he do that every time when I'm pitching?" Hughes said jokingly of Rodriguez. "That was unbelievable. Two of the three balls were balls [out of the strike zone], too. When he gets locked in, it's pretty fun to watch.
"I'm really lucky to have a great offense behind me, anytime you can look up and see that. I feel like I've been throwing the ball OK here and there, and it seems like we've been scoring enough runs to win. It's a nice feeling."
Wilson Betemit had an RBI single in the first inning and a solo homer in the sixth, an inning that saw Hughes have to work out of trouble when Brett Gardner lost a Yuniesky Betancourt fly ball in the lights for a single.
"It got above the lights of the stadium, and that's when you lose it," Gardner said. "I just went to where I thought it was going to fall once I didn't see it anymore and hoped it would reappear. It never did."
Kansas City scored its third run on a RBI groundout, but Hughes held the damage there, scattering nine hits while walking one and striking out none.
"You look at the box score and it's not great, but a couple of them kind of bled through there," Hughes said. "A couple of things didn't go my way and I had to battle through that inning, which you really don't want to do."
Of course, Hughes would have been fine had he known what would transpire. Rodriguez's power has been a topic of discussion, despite the fact he entered play Saturday second in the American League to Detroit's Miguel Cabrera in RBIs.
Part of that was the high profile of Rodriguez's chase for No. 600, which saw him endure 42 homerless at-bats and a 0-for-17 skid at the plate before finally hitting it on Aug. 4. Though Rodriguez had maintained he was fine just being a cog in the machine, a three-homer showing sure tasted sweet.
"I haven't really hit for any power this year. It's been frustrating," Rodriguez said. "The idea of being stuck at 599 really was a microcosm of what's happened all year. I've hit some home runs and some doubles here and there, but overall, I've played with no power."
The Yankees know better than to count Rodriguez out. A-Rod missed all of April last season due to right hip surgery and appeared likely to see his 11-year string of 30-homer, 100-RBI seasons end on the season's final day before he had another remarkable day, homering twice and driving in seven runs.
The RBIs won't be a problem for Rodriguez, who now has 97 in the column running next to his name on the stat sheets. And with 46 more games on the Yankees' schedule, they also won't be surprised if he happens to hit nine or more home runs to keep that power show running for another season.
"I wouldn't," Girardi said. "I think a lot of times, a player's home runs come in bunches. And they came in a bunch today."