Odalis Perez (8-11) recorded his first career decision against Oakland, winning back-to-back starts for the first time since April 20 and 25, and Kansas City owns its first three-game winning streak since getting four straight victories from July 26-29.
Perez pitched five shutout innings and has a combined 15 scoreless innings against the A's in three appearances.
A's second baseman Mark Ellis thought he had seen his Oakland record errorless streak at the position end at 81 games in bizarre fashion. With Joey Gathright heading to second on St. Mary's College product Mark Teahen's bouncing grounder in the fifth, Ellis charged in on the ball and made contact with Gathright.
Ellis fumed moments later believing that Gathright was out on interference and made a rare argument to second base umpire Mike Muchlinski. A's manager Bob Geren hustled out and separated them, then began yelling himself. Geren, who was also calling for interference on the runner, was ejected -- the second time the rookie skipper has been tossed.
An inning later, Teahen was credited with a single and Ellis' error was removed.
Smith hit just his third homer of the year in the second and had another in the eighth for his third career multihomer game.
On a night both starters had problems with command, the A's rallied against reliever Joel Peralta in the sixth. Jack Cust led off the inning with a triple, Mike Piazza followed with an RBI double and Jeff DaVanon tripled in a run one out later. Donnie Murphy followed with a sacrifice fly that pulled Oakland within 4-3, then Jack Hannahan's walk chased Peralta.
David Riske entered and got Kurt Suzuki on an inning-ending fly out.
Perez worked through Oakland's order until allowing three straight two-out walks to Shannon Stewart, Nick Swisher and Cust to load the bases in the third. He went to 3-1 on Piazza, but the designated hitter flied out to shallow left.
Perez allowed three hits, struck out two and walked four in his first outing against Oakland since pitching in relief on June 18, 2006, while with the Dodgers.
Chad Gaudin (9-9) lost for the sixth time in his last seven decisions. He won at Detroit in his previous outing Aug. 13 following a six-start winless stretch in which he went 0-5 since a victory July 5 against Seattle.
The A's featured five players in the starting lineup who weren't on the Opening Day roster, including three who weren't even in the organization back in April.
DaVanon, released by Arizona earlier this month, played center field in his first start with the A's after getting one at-bat Friday night after being called up from Triple-A Sacramento.
Notes: The victory marked the 100th franchise win for the Royals in Oakland . . . Smith's last two-homer game came April 9, 2006, at San Diego while with Colorado. Fourteen of his 15 career homers have come on the road. . . . Swisher leads the A's with 90 walks. . . . The Royals are 18-12 against the AL West, and have four more games to go with their former division rivals -- Sunday's series finale with the A's and three games at Texas in early September. . . . Oakland's five losses to Kansas City at home are the most for the A's against the Royals since dropping four games in 1995. . . . Tony Pena drew his second walk since May 5 starting the seventh.