KANSAS CITY -- Mark Mulder gave Oakland's bullpen the night off -- again.

Mulder threw a four-hitter Saturday night for his second straight complete game and 19th of his career, outdueling Kansas City's Darrell May in the Athletics' 3-1 victory over the Royals.

Eric Chavez hit a two-run homer for Oakland, which won for the seventh time in nine games.

Mulder (4-2) gave up four hits and had a season-high seven strikeouts while improving to 7-0 against Kansas City. That followed his 8-4 win at Minnesota last Sunday.

"I feel good," he said. "I'm not going to say after seven, 'OK, I'm done. I don't want to hurt myself.' That's not going to happen."

Kansas City lost its sixth straight to Oakland, all at home, and lost a chance to win back-to-back series for the first time this season.

May (1-5) retired the last 11 batters he faced in his first complete game of the season, and gave up five hits -- but one of those was Chavez's homer that gave the A's a 3-0 lead in the sixth inning.

After Bobby Kielty doubled to left with one out, Chavez bounced an 0-2 pitch off the top of the wall in left center for his 10th homer.

The pitch was so far out of the strike zone that May never expected Chavez to swing at it.

"I went back and looked at the video later, and it looked like a great pitch -- a hard slider, down and away," May said. "If I had to do it all over again, I'd throw the same pitch."

And if Chavez had to do it again, he'd probably swing.

"He threw me a couple of fastballs down the middle today, and I didn't pull the trigger for one reason or another," Chavez said. "His 0-1 slider was actually a better pitch than the 0-2 slider, but for some reason I hit better out of the zone than I do in the zone."

The A's went hitless through 3 1-3 innings before Chavez singled and scored on Scott Hatteberg's double for a 1-0 lead in the fourth.

Joe Randa finally put Kansas City on the board with a leadoff homer in the seventh.

May had six strikeouts and one walk in his first complete game since shutting out Texas 9-0 on Aug. 27, 2003, but couldn't keep the Royals' staff from falling to 1-10 against the Athletics.

"May did a great job today, but we couldn't get to Mulder," said Carlos Beltran, who was 0-for-4 with a strikeout for the Royals. "We had opportunities, but we weren't able to get hits."

Kansas City manager Tony Pena shuffled his lineup, dropping shortstop Angel Berroa from the leadoff spot to No. 8. Second baseman Desi Relaford took Berroa's leadoff spot.

"He has not been swinging the bat well, and he has been chasing a lot of pitches," Pena said of Berroa, last season's AL Rookie of the Year in 2003. "We're going to get him out of there until he gets settled down."

Neither did much in the revamped order, though. Berroa was 0-for-2 with a sacrifice bunt, and Relaford was 0-for-3 and struck out twice.