KANSAS CITY, Mo. -- Jason Vargas threw a three-hitter and second baseman Omar Infante hit a two-run homer as the Kansas City Royals shut out the Oakland Athletics 3-0 on Wednesday night.

Vargas, who gave up two hits in the first, retired the final 23 batters. It was his 11th career complete game and his sixth shutout. His previous shutout was Sept. 24, 2013, against the A's while with the Angels.

The Royals (65-54) have won 12 of 14 and remain in first place in the American League Central, a half-game in front of the Detroit Tigers.

Vargas (8-6) struck out four and walked none. He allowed only one batter past first base. He threw 23 of his 97 pitches in the first inning and needed only five pitches in the ninth. He did not throw more than 13 pitches in an inning after the eighth.

Left-hander Scott Kazmir (13-5) absorbed the loss, giving up three runs on seven hits, with Infante's third-inning blow the biggest.

Infante, Kansas City's second baseman, homered in the third inning after right fielder Nori Aoki singled as the Royals grabbed a 2-0 lead. Infante hit a 2-0 pitch over the Royals' bullpen in left field for his first home run since June 27, a span of 149 at-bats.

The Royals threatened in the fourth inning when designated hitter Josh Willingham singled to left, stole second and moved to third with one out on Kazmir's errant throw on a pickoff attempt. Willingham, however, was stranded as center fielder Lorenzo Cain grounded out and Kazmir struck out shortstop Alcides Escobar.

Vargas, who was making his third start since an appendectomy last month, pitched his way out of trouble in the first inning. After retiring the first two batters, third baseman Josh Donaldson doubled and moved to third on designated hitter Jonny Gomes' infield single. Vargas struck out catcher Mike Norris to end the inning.

The Royals manufactured a run in the fifth inning, which rookie third baseman Christian Colon started with a bunt single. Aoki's sacrifice bunt moved Colon to second and he went to third on Infante's infield single. Catcher Salvador Perez flied out to right, deep enough to bring Colon home.

NOTES: A's 1B Kyle Blanks, who has missed 43 games with a left calf strain, is 3-for-5 with three walks and a home run in two rehab games for Triple-A Sacramento. ... Royals rookie INF Christian Colon started his second game at third base. 3B Mike Moustakas, who is hitting .145 against left-handers, was given the night off. ... Royals RHP James Shields, who has a 1.63 ERA since July 7, will start the series finale against the A's. Oakland's starter will be RHP Jeff Samardzija, who has yielded six home runs in 49 2/3 innings with the A's. ... The A's went into the game Wednesday outscoring the opposition by 175 runs, more than double the next-closest team.