OAKLAND -- As if he needed one at all, manager Bob Melvin kept his explanation for placing Yoenis Cespedes in the cleanup spot Saturday rather brief.

"What the heck?" he said, smiling.

His grin proved contagious with surrounding reporters, considering everyone was still thinking about the outfielder's second home run in three games Friday night -- a tape-measure shot calculated by ESPN at 462 feet.

"He's a power bat, and we'll continue to move [the lineup] around a bit, but I think he's swinging pretty well," Melvin said. "You're going to see some strikeouts, but you're also going to see a guy that's going to run into one, and when he does and there's somebody on base, it's usually worth a couple, so he'll hit fourth today."

Against one of the game's best, no less. For the second time already this season, the A's on Saturday were forced to face Seattle ace Felix Hernandez, who has a 2.47 ERA with 148 strikeouts in 22 career starts against Oakland. Cespedes is responsible for one of those strikeouts, but he also doubled off the righty in his other at-bat in Tokyo last week.

Elsewhere in the lineup, Josh Reddick made his second straight appearance in the third hole, while Brandon Allen got the nod at first base and Eric Sogard started at third. Melvin said Sogard will continue to see action against right-handers but that Josh Donaldson will still receive the majority of starts at the hot corner.

"Our whole lineup is still a work in progress," Melvin said. "We're trying to find the right mix. We have a lot of new guys here that have not played together before, and we had a shortened spring. This is the first time we're able to get the same group out there, so it's going to be mix and match."

A's face Barton decision on Sunday

OAKLAND -- The A's on Sunday will have to decide whether to activate Daric Barton from the disabled list, a move that would likely lead to the designation of one of the other two first baseman already on the roster.

Left-handed hitters Brandon Allen and Kila Ka'aihue, both out of options, have alternated at first base in Oakland's first four games -- a scene not likely to change until Barton's arrival. But manager Bob Melvin said Saturday he's not quite sure whether Barton, who is strengthening his surgically repaired right shoulder via a rehab stint with Triple-A Sacramento, is prepared for big league action. He's eligible to be return from the DL on Sunday, when the A's are set to enjoy an off-day before beginning a three-game home series with the Royals on Monday.

Barton played in an exhibition game with Sacramento on Tuesday and, since the River Cats' off-day Wednesday, has played in each of their games since, going 3-for-9 with one walk and three strikeouts.

"It's all about playing multiple days in a row with him and feeling comfortable with it, knowing he can go out there, whether it's a week in a row, and not worry about his shoulder," Melvin said. "I think it's just as much mental right now as it is physical, because you don't want to go out there playing when you're thinking about something. So I think that's the last hurdle for him."

Ka'aihue started Friday's home opener at first base, going 2-for-4 with a pair of base hits -- numbers that would normally influence a manager to keep him in the lineup the next day, except most managers aren't trying to get two left-handed hitters playing time at the same position, as Melvin is. So Allen got the start Saturday, with the game of musical chairs expected to continue until further notice.

"That was the toughest decision today, not putting Kila in the lineup again," Melvin said. "We'll see how it goes, and you can use them off the bench, too."