After winning 4-2 in Monday's opener at Oakland, Kansas City (49-59) beat the A's 5-2 on Tuesday and now tries for its first three-game sweep in the East Bay since June 14-16, 1988.

John Buck hit a three-run homer and rookie shortstop Mike Aviles added a solo shot Tuesday for the Royals, who will try for a fourth straight victory overall while looking to send the Athletics (53-53) to a third consecutive defeat and 11th in their last 13 contests.

The Royals have hit six homers in their last three games, including four in this series.

"We had some slug; two days in a row," Royals manager Trey Hillman said. "These guys like hitting here, obviously."

Aviles is 8-for-18 in his last four contests and batting .318 with six home runs and 27 RBIs since being called up from the minors on May 29.

Buck, meanwhile, has two of his eight homers in his last four contests.

Brian Bannister (7-9, 5.40 ERA) takes the mound for the Royals trying to avoid a fourth consecutive loss. He allowed two earned runs and seven hits in 5 1-3 innings of a 5-3 loss to Tampa Bay on Friday.

"My ball had a little more life and action to it," said Bannister, who despite a solid performance fell to 0-3 with a 9.12 ERA over his last five starts.

The right-hander is 1-1 with a 4.05 ERA against the A's and allowed five runs in five innings of a 13-2 loss at Oakland on April 18.

Mark Ellis and Bobby Crosby each drove in a run Tuesday for Oakland, which has scored three or fewer runs nine times in its last 13 contests. The A's are also on the verge of falling below .500 for the first time since they were 3-4 on April 8.

"It's not fun scoring two runs a game," Ellis said. "But you have to work and keep working and keep trying to have good at-bats and make the pitchers work a little bit more."

Sean Gallagher (1-0, 2.60) makes his fourth start for the A's since coming over from the Chicago Cubs in the deal for pitcher Rich Harden on July 8.

The right-hander won his Oakland debut on July 11, but has failed to earn a decision in either of his last two starts. He allowed five runs - one earned - and nine hits while walking five and striking out five in 5 1-3 innings of a 14-6 loss to Texas on Friday.

"I just left way too many balls up in the zone," Gallagher told the A's official Web site. "I felt like I kind of let (my team) down."

Gallagher will make his first appearance against Kansas City on Wednesday.