OAKLAND, Calif. (AP) -- Yoenis Cespedes hit a leadoff home run in the eighth inning and the Oakland Athletics beat the Kansas City Royals 4-3 on Sunday to complete a three-game sweep.

Cespedes hit his eighth homer, connecting against Kelvin Herrera (2-4).

Jerry Blevins (3-0) pitched one scoreless inning. Ryan Cook worked the ninth for his first save of the season.

Alex Gordon matched his career high of four hits for Kansas City. The Royals have lost 10 of 13 and fallen back to .500.

Held in check by Kansas City starter Luis Mendoza most of the afternoon, the A's benefited from a costly error by center fielder David Lough that allowed the tying run to score in the seventh.

Oakland's first sweep of the Royals since 2008 didn't come easily.

The A's squeaked out a pair of 2-1 wins on Friday and Saturday, then had to sweat out another tight finish in the series finale.

Cook, pitching because closer Grant Balfour was unavailable, allowed two-out singles to Billy Butler and Eric Hosmer in the ninth. Mike Moustakas then worked a full count off Cook before grounding out to end the game.

The Royals helped Oakland's comeback when Derek Norris hit a leadoff single in the seventh and raced to third when the ball skipped over Lough's glove and rolled to the fence. One batter later Coco Crisp's sacrifice fly tied it.

Mendoza struck out four and didn't walk a batter for a second straight start.

Gordon hit an RBI single in the third, scored in the fifth and doubled in the seventh. Since moving to the third spot in the lineup on May 9, Gordon is batting .450 (18 for 40).

The Royals, who scored just two runs and stranded 11 baserunners in the first two games of this series, went up 2-0 when Chris Getz singled in Hosmer in the fourth. Hosmer added an RBI double in the fifth.

A's starter A.J. Griffin had command problems most of the day. He walked three and struck out five but failed in his bid to become the second pitcher in Oakland history to reach 12 wins in his first 24 starts.

Josh Donaldson had a sacrifice fly in the Oakland fourth and Jed Lowrie had an RBI single in the fifth.

NOTES: Gordon had 60 multihit games in 2012 but already has 20 in the Royals first 40 games this season. He has nine career four-hit games. ... Injured Oakland OF Josh Reddick continues to make slow progress from surgery on his right wrist. He was out Sunday after taking swings off a tee the previous day and is eligible to come off the disabled list Wednesday, though manager Bob Melvin thinks Reddick will need more time to heal. ... Kansas City RHP Jeremy Guthrie (5-1) pitches the series opener in Houston and is seeking to rebound from his first loss of the season. ... A's RHP Bartolo Colon (3-2), who takes the hill against Texas on Monday, is winless in his last four starts.