OAKLAND, CALIF. ? Michael Tucker hit a 405-foot single.

Tucker’s 10th inning homer turned into a base hit because of a base-running mistake, but it still gave the Kansas City Royals a 4-3 victory over the Oakland Athletics on Saturday.

Kansas City's Michael Tucker, right, argues with second base umpire Bill Miller. Tucker was called out for passing Mike Caruso between first and second base during the 10th inning against the Athletics on Saturday in Oakland, Calif.

Joe Randa singled to left to lead off the 10th off Billy Koch (5-1). An out later, Tucker’s hit sailed over the fence in dead center, but he passed pinch-runner Mike Caruso between first and second base.

Caruso said he thought the ball was caught by Oakland center fielder Terrence Long, who made a leaping grab and momentarily looked like he had it, but lost it when he hit the wall.

Tucker got an RBI single, was out on the way to second and only one run scored.

“I wasn’t sure about Long catching it, but Caruso caught me,” Tucker said. “That was a long single, a 405-foot single.”

Caruso said he first thought Long made the catch.

“I didn’t really head back, I just took a couple of steps,” he said. “I was looking out at Long, Tucker was looking at Long and the first base coach was looking at the umpire to see if he called it a home run. I was passing Tucker and he was passing me. We were going in different directions.

“I felt bad for Tucker, because he hits a home run and doesn’t get any credit for it.”

Scott Mullen (1-2) pitched the ninth for his first big league win as the Royals snapped a three-game losing streak. Brad Voyles pitched the 10th for his first major league save.

“I think I’ve seen it all, then today, wow!,” Royals manager Tony Pena said.

Long said he had the ball, but it fell out of his glove when he hit the wall. He was confused as everybody else about what happened next, and was looking in toward the field when the homer was ruled an RBI single.

“I still don’t know what happened,” Long said. “So what happened?”

The strange play gave A’s manager Art Howe hope Oakland could pull it off in the bottom of the 10th. With six straight one-run games, the A’s have won three times with bottom-of-the-ninth plays.

“Something told me, we might just win this one because of what happened,” Howe said. “But we didn’t have a miracle today.”

With the A’s down 3-2 in the eighth, Miguel Tejada doubled off Kris Wilson to extend his hitting streak to 11 games, then scored on David Justice’s single to shallow right to tie it.

That spoiled a fine outing by Darrell May, who allowed two runs on five hits over six innings. He was vying for his first victory since a rain-shortened 6-0 shutout in Florida on June 11, five starts ago.

May struck out the side in the sixth and finished with a career-high nine strikeouts.

A’s rookie right-hander Aaron Harang opened well, striking out the first three batters he faced. The A’s gave him support, going up 1-0 in the bottom of the first on Eric Byrnes’ RBI single.

But Harang spent the next two innings getting out of trouble.

Neifi Perez hit an RBI single to tie it in the second before Harang loaded the bases with just one out. He escaped by striking out Brent Mayne and Carlos Febles.

In the third, Harang loaded the bases with two outs before striking out Perez. Harang threw 40 pitches in the inning.

The A’s retook the lead in the bottom half on Tejada’s double-play grounder off May with the bases loaded.

Aaron Guiel tied it back up for the Royals in the fourth with an RBI grounder, and Carlos Beltran added a go-ahead run-scoring double before Harang was pulled.

Harang allowed three runs on seven hits over 3 2/3 innings with six strikeouts.

Kansas City first baseman Mike Sweeney, headed to his third straight All-Star game, was out of the lineup for the third consecutive game.

Sweeney had two stitches in his right ring finger after getting hit by a pitch from Seattle’s Joel Pineiro on Wednesday. Sweeney is listed as day-to-day.

Notes: Left-handed pitcher Ted Lilly, acquired by the A’s in a three-team trade between the Yankees and Detroit early Saturday, was expected to join the team on Sunday. A’s manager Art Howe said Lilly would be in the bullpen for the series finale against the Royals, before joining the starting rotation. … The A’s did not immediately make a corresponding roster move to make way for Lilly. … Right-hander Paul Byrd (11-5), Kansas City’s starter on Sunday, is vying to become the first Royals pitcher to win 12 games before the All-Star break since David Cone, who went 12-4 in 1994.