They helped New York remain three games ahead of Detroit in the American League Wild Card race and win its fourth straight game, the club's longest winning streak since Aug. 10-13. The Yankees are 8-1 against the Royals this season.
Pettitte tossed 6 1/3 innings of two-run ball and A-Rod hit his 50th and 51st homers of the season off Brian Bannister, setting a Major League record with 49 homers as a third baseman to break the mark previously held by Mike Schmidt and Adrian Beltre.
He became the first Yankees player to hit 50 homers in single season since Roger Maris and Mickey Mantle hit 61 and 54, respectively, in 1961. A-Rod, though, believes that his numbers -- and his veteran teammates' numbers -- wouldn't be the same without the youngsters.
"My teammates have had a lot to do with my success this year," Rodriguez said. "You take guys like Pettitte and Roger [Clemens], new guys coming in with a different perspective who have been there before. Obviously, the young guys -- all of them -- not only bringing energy to me, but other veterans on this team."
And the Yankees certainly had plenty of fun on Saturday night. Rodriguez's first homer, a two-run shot, came off Bannister in the fourth inning. The second homer, a solo shot, started New York's seven-run sixth inning, which ended Bannister's day.
New York was seeing Bannister, 7-1 in his last nine starts and arguably the best rookie pitcher in the Majors this season, for the first time this year.
Bannister, who entered the game with a 3.16 ERA, fourth best in the AL , kept the Yankees under control through the first five innings, allowing four runs.
The Yankees awoke in the sixth.
Leading, 4-2, New York saw 12 men bat and finished the inning with a nine-run lead. After A-Rod's homer, Hideki Matsui and Jorge Posada followed with walks against Bannister.
Ryan Braun relieved Bannister and Robinson Cano sacrificed the runners. Then Betemit crushed a three-run homer over the center-field fence. Cabrera then singled, and Johnny Damon doubled.
Alberto Gonzalez, who entered the game for Derek Jeter after the All-Star shortstop exited with right knee stiffness, hit a ball that traveled barely 30 feet, and Braun tried to throw home for the force, but Cabrera slid across the tag. Bobby Abreu crushed a two-run double to left-center field, pushing New York into double digits for the third time in four games.
In their four straight wins, the Yankees, who lead the Majors in second-half runs, have outscored opponents, 39-10.
In his second at-bat of the sixth inning, Rodriguez nearly followed with his third homer of the game, flying out to deep right-center field.
Pettitte, who suffered through his worst second-half start in his last outing, allowing five runs in 6 1/3 innings, bounced back with a quality start. He pitched 6 1/3 innings and improved to 9-2 since the All-Star break. In those 12 starts, Pettitte has allowed three earned runs or fewer 11 times.
"I have been going pretty hard for the past month or two and have been feeling really strong and kind of hit a little bit of a wall tonight," Pettitte said. "[Manager Joe Torre] knew I was a little bit gassed out there.
The victory, Pettitte's 162nd as a member of the Yankees, tied him with Herb Pennock for seventh place on the Yankees all-time list and moved him to fourth among club left-handers all time.
Other than two fourth-inning runs, Pettitte cruised. He allowed seven hits and two walks and permitted the leadoff hitter to reach base on one occasion. The left-hander hasn't lost to Kansas City in his last eight starts.