PHOENIX -- It may have been a big day for Yoenis Cespedes, but Saturday was just as big for Bartolo Colon as the A's downed the Reds, 6-3, at Phoenix Municipal Stadium.

The Cuban-born Cespedes homered and had an RBI single in his first three Cactus League at-bats, and veteran right-hander Colon set down the Reds on one run and three hits with four strikeouts over four innings. Colon threw 52 pitches, 39 for strikes.

Colon, who pitched last year with the Yankees after missing the entire 2010 season because of right shoulder and elbow injuries, is slated to start the A's second game of the season against the Mariners at the Tokyo Dome on March 29, so he's on an accelerated schedule this spring.

Reds third baseman Juan Francisco had the only extra-base hit off him -- a fourth-inning double. Colon took Todd Frazier's grounder off a leg during the fourth, but he stayed in to retire the next hitter and finish the inning.

Reds right-handed starter Johnny Cueto walked Cespedes on six pitches in the first inning and allowed Cespedes' RBI single in the second.

"I don't think about any names. I just want to get this guy out," Cueto said. "He looks like he had some idea at home plate."

Cespedes blasted his homer off left-hander Jeff Francis to open the bottom half of the fourth. Francis had just come into the game and faced the leadoff-hitting Cespedes, throwing a plethora of breaking balls that the right-handed hitter kept fouling off to the left side. Cespedes had fouled off four consecutive pitches before launching a fastball over the left-field fence.

Manny Ramirez returned as the A's designated hitter on Saturday after missing three games because of a sore back. He went 0-for-3, and reached on an error in his final at-bat.

Reds up next: Third baseman Scott Rolen is batting .556 (5-for-9) with two RBIs and appears to be feeling good after an injury-filled 2011. Rolen and the Reds will host an Angels split-squad on Sunday in Goodyear, Ariz., at 4:05 p.m. ET. Jay Bruce will also play and serve as the designated hitter and get at least four at-bats. Mat Latos is scheduled to make his second spring start, and will be followed by Brett Tomko, Ron Mahay, Jose Arredondo and Logan Ondrusek.

Athletics up next: Manager Bob Melvin said that Cespedes will be the DH in Sunday's home game against the Royals at 1:05 p.m. PT. He added that he had made no further plans for Cespedes for games next week, saying that he was just taking it day to day for the moment. The A's are still searching for three starters at the back of their rotation, and one of the top candidates, left-hander Tommy Milone, will make his second start. He'll face Royals left-hander Bruce Chen.