Edward Olivares hit two home runs in his return from the injured list as the Kansas City Royals defeated the visiting Oakland A's 3-1 Friday night in the first game of a three-game series.

Olivares had not played a game in the majors since May 8.

The Royals have won six of their last eight games, while the A's have lost 19 of their last 22.

Zack Greinke (1-4) earned his first win of the season. He allowed one run on three hits in six innings. He didn't walk a batter and struck out four. Greinke improved to 12-3 all-time against the A's.

Scott Barlow picked up his ninth save in 11 chances.

Greinke had been out since May 30 with a right flexor strain. He had an ERA of 9.50 with 15 strikeouts, seven walks and five home runs allowed in his last four starts before going on the injured list.

Cole Irvin (2-6) took his second straight loss against the Royals. He allowed three runs on seven hits in 5 1/3 innings.

Olivares hit his first home run of the season to put the Royals on the board in the third. Olivares, who blasted one 430 feet to left, had been out since May with a right quad strain. He took the spot on the roster of Salvador Perez, who had surgery Friday to repair the ulnar collateral ligament on his left thumb.

The A's answered with a run in the fourth. Tony Kemp led off with a single. He stole second and scored on Seth Brown's two-out single up the middle.

Olivares put the Royals on top in the fifth inning with his second home run of the game. As in his first at-bat, Olivares pounded a solo home run to left field.

The Royals added another run in the sixth on an RBI single by Carlos Santana. Hunter Dozier led off with a double, followed by a walk to MJ Melendez.

Santana pulled the ball to left and was thrown out trying to stretch it to a double. It was his ninth RBI in his last 13 games.