OAKLAND -- Right-handed pitcher Rich Harden threw from the mound Saturday for the first time in nearly two months.

Harden, who is on the 60-day disabled list, has been sidelined with lat muscle soreness under his throwing arm and has yet to pitch this season. But the hurler, who signed a one-year deal worth $1.5 million as a free agent in the offseason, tossed two side sessions in the past week on Saturday and Tuesday.

Although the throwing sessions are a positive step for Harden, A's manager Bob Geren said the righty is still a long ways away from throwing simulated games. In the meantime, Geren said he is just looking to make sure Harden feels good during the throwing sessions and is "free and easy."

"[Tuesday] was better than his first one, which was encouraging," Geren said. "He's just continuing to follow that plan, from long toss, to on the mound and build up from there."

Harden will travel with the team when it embarks on a 10-game road trip, and Geren said the plan is for Harden to throw another session on Friday in Boston.

A's give Barton time to find confidence, swing

OAKLAND -- Following Daric Barton's 0-for-4 showing in Monday's loss to the Yankees, A's manager Bob Geren noted he would consider moving his first baseman down from the second spot in the batting order.

Sure enough, Barton wasn't there when Tuesday's lineup was posted. In fact, his name wasn't even found among the starting nine, as Conor Jackson was handed a start at first base, hitting behind David DeJesus' No. 2 slot.

"Barton's been struggling a little bit," Geren acknowledged. "We'll give him time to get him right, and I think maybe a day or two or so away from the lineup to do that and do a few things to get his mind right on his swing and his approach is probably best for him."

That means Barton's lineup absence could extend through the week, as he attempts to target unfamiliar struggles, evidenced by his .206 season average. He's 3-for-24 over his past seven games and is batting .177 in his past 38.

"It's just one of those things [where] you have to find something, anything that clicks in your head or at the plate," Barton said. "I'm not feeling too comfortable out there, so that's been something that's been bugging me. I've never really had a problem feeling comfortable up there.

"There are a lot of things that go on in your mind when you go through something like this, so it's tough, but it's part of the game and it's my job to figure out what to do to get back to success."

Barton, 26 years old and a career .260 hitter in four seasons with Oakland, currently owns the American League's third-lowest slugging percentage (.270) among qualifying players and is the only Major League first baseman with more than 75 at-bats that has yet to homer this season.

Well-known for his plate discipline, Barton still ranks among the top 10 in the AL with 31 walks, but he's also tallied 39 strikeouts, second-most on the A's behind Josh Willingham's 56. Though he feels like he's put together decent at-bats, Barton admitted to neither attacking the zone nor letting the ball travel enough.

"I seem to be getting deep into counts, just not putting consistent swings on pitches that I should be hitting," he said.

"We've looked at some video, and his swing doesn't look all that much different from when he's really been hot," Geren said. "I just think that, mentally, when you're not getting hits you start thinking a lot. You have to take a step back and go back to some basics. That's what he's going to do. He's going to spend some time tracking pitches, spend some time bunting, spend some time working on some specific drills.

"He's a good hitter, and he's always hit, and he will hit. We'll do whatever we can to try to help him."

Barton wasn't opposed to the mental day off, or the possibility of another one. In fact, he thinks it could be just what he needs.

"Let's hope," he said. "I'm trying anything right now, so it'll be good to relax for a day and not have to stress myself out."

Upon his return, Geren said he would still consider placing Barton elsewhere in the lineup, but also noted "he's a perfect No. 2 hitter when he's swinging."

"Whether a few adjustments, a couple days here, move him down, whatever can help him help the team, we'll do," he said.

Sweeney in lineup as Matsui sits out

OAKLAND -- Hideki Matsui was held out of the A's starting lineup on Tuesday for the 14th time this season, a nod to the veteran's continual struggle to find any consistency at the plate.

Matsui is hitting .222 on the season and has collected 14 hits in 71 at-bats in the month of May. If history is any indication of what could be, though, Matsui's bat could potentially wake up with the flip of the calendar on Wednesday.

Matsui is a .300 career hitter in June and also boasts a .307 average in the month of July, numbers far superior to his current performance, which also includes a .277 on-base percentage and .390 slugging mark.

"You go into each game, and you try to win every single game," manager Bob Geren said. "When guys are swinging the bats, you try to keep them in there. When guys are struggling, you have to put other guys in there. I have confidence he's going to hit. He's always hit."

In Matsui's stead, Josh Willingham served as designated hitter against Yankees starter Freddy Garcia while Ryan Sweeney got a start in left field -- a configuration that could be copied again.

"We'll go day to day," Geren said. "I know [Matsui] hasn't been swinging as well as he would like and Ryan, when giving the opportunity, has swung well."

Rosales to begin rehab assignment Wednesday

OAKLAND -- Infielder Adam Rosales returned to the A's clubhouse Tuesday, if only momentarily.

Rosales, who underwent foot surgery in December, made a stop in Oakland on Tuesday afternoon to pick up some bats before he made his way to Sacramento to begin his rehab assignment with the Triple-A club. The infielder was going to take batting practice with the team, but on-field batting practice was canceled due to rain.

After a stint in Arizona for some extended spring training games, Rosales will make his first rehab start in the Minors on Wednesday against Salt Lake City. A's manager Bob Geren said Rosales will play seven innings at third base Wednesday, then play shortstop the next day, but will move around the infield as his rehab progresses.

"Everything's gone perfect in his rehab and he's feeling pretty good," Geren said. "He's building up his legs and building up his at-bats to get his timing right."

Barring any unforeseen setbacks, the team is targeting the middle of June for Rosales to make his return to the club.

As soon as Rosales is ready and back to 100 percent, Geren hinted that he would be reactivated to the A's roster and likely reclaim the backup infielder spot currently manned by Andy LaRoche. In 37 games this year, LaRoche is hitting .233 with five RBIs and nine runs scored while sporting a .947 fielding percentage at all four infield positions.

"When [Rosales] is ready, we know he's a great player," Geren said. "He's feeling good and he's performing well, too. It's just a matter of time before he's 100 percent."

Worth noting

Prior to Tuesday's game, the A's honored Dairyland Elementary School fifth-grader Morgan Dill, who won the 2011 Breaking Barriers: In Sports, In Life essay contest.

The A's, along with Sharon Robinson, the daughter of Hall of Famer Jackie Robinson, held a ceremony to recognize Dill, whose winning essay was about her efforts to overcome a liver transplant.

Earlier in the day, Robinson visited Dill at school and spoke to students about her father, as it related to the Breaking Barriers: In Sports, In Life program, a multi-curricular character education program developed by MLB and Scholastic, Inc.

• Cliff Pennington, despite riding a nine-game hitting streak, was given a day of rest on Tuesday, while Andy LaRoche got the start at shortstop.

"His body is in definite need of a day off," Geren said. "He's been doing great, and we want to keep it that way."

• The start time of Saturday's game at Fenway Park in Boston has been moved from 4:10 p.m. PT to 10:10 a.m. According to the Red Sox, the game will start earlier so that fans can enjoy both the baseball game and the NHL Stanley Cup Finals between the Boston Bruins and Vancouver Canucks that night.