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6/12/2013 10:51 P.M. ET

Overbay's exposure to outfield a work in progress

OAKLAND -- Joe Girardi tempted fate before Tuesday night's game against the Athletics when he noted that Lyle Overbay had been flawless in his first three games playing right field in the big leagues.

Though no error was charged, Overbay's inexperience showed in the second inning of the Yankees' 6-4 loss as the longtime first baseman allowed Derek Norris' soft double to fall between him, second baseman Robinson Cano and first baseman Mark Teixeira, driving in Oakland's second run.

Girardi said that he is not rethinking the experiment of having Overbay play the outfield, an avenue to keep him active on the roster now that Teixeira has reclaimed first base.

"It's something new for him, that's the bottom line," Girardi said. "There is a learning curve. We expect that he can make it pretty quickly. He'll make the adjustments."

Overbay, 36, was drafted as an outfielder by the D-backs but converted to first base early in his Minor League career, playing just 30 professional games in the outfield before this season.

He has been working with third-base coach Rob Thomson on positioning and various scenarios, and said that his mistake was not taking into account how challenging of a play Norris' bloop presented for Cano from second base.

"I didn't think that I could catch it, so I figured, let Robbie try," Overbay said. "I think if I had it all over again, he was playing up the middle so I should've known that he wasn't going to have a chance to get it. Maybe I could lay out or something. I knew I couldn't get it, so I was kind of hoping he might have a chance."

Mo surprises A's employee with pregame pizza

OAKLAND -- Mariano Rivera's "Mo-ment of Thanks" tour has taken place behind the scenes at several ballparks around the Majors this season, bringing visits to areas that the Yankees closer normally doesn't see.

Rivera discovered on Wednesday that gaining access to the less-traveled areas of a ballpark is much easier while carrying a piping-hot pizza pie.

The retiring hurler surprised long-time Athletics employee Julie Vasconcellos before Wednesday's game at the O.co Coliseum, delivering an early dinner to her mail-room office. They spent about 30 minutes together before Rivera took the field for batting practice with his teammates.

"This is my way to say thank you, thank you for what you do," Rivera told Vasconcellos, according to The Associated Press. "Twenty-five years, Julie, that's great! You're special, Julie, that's what it is. People here love you."

Rivera has said that he wants to take the opportunity to thank diehard fans and long-time club employees at each of the Yankees' road stops this season.

Vasconcellos, the A's office services coordinator, has worked for the club since 1989 and is involved in aspects of the organization ranging from the front office to the mail needs of the home and visiting clubhouses.

"Oh, my heart's going to town, oh my God," Vasconcellos told the AP. "I'm shaking. ... Oh, this is too funny, thank you."

Pineda's next outing shifts to simulated game

OAKLAND -- The Yankees have made a change of plans with rehabbing right-hander Michael Pineda, who will make his next appearance on Friday in a simulated game rather than pitching for a Minor League affiliate.

A change was made because the Yankees would prefer to have Pineda pitch under controlled conditions, according to manager Joe Girardi, who said that there are no injury concerns with the 24-year-old.

"This way, we can control it," Girardi said. "The other day he had one long inning and sometimes you worry about a guy that's rehabbing. This way you can build him up easier; he doesn't have to travel. Physically he's fine. Tuesday he threw his bullpen and he's ready to go."

Pineda allowed an unearned run over 4 2/3 innings on Sunday for Class A Tampa at Lakeland, but the Tampa Yankees are off on Friday for the Florida State League All-Star break.

"It's one start, it's not a big deal," Girardi said. "It will probably be the only simulated game he throws. It just works out better."

The Yankees expect Pineda to throw 75 pitches in his simulated game and continue to project that he should be a choice for the big league roster sometime in July, though general manager Brian Cashman has left open the possibility that Pineda could be sent to start at Triple-A Scranton/Wilkes-Barre when his rehab assignment is complete.

Bombers bits

• Girardi said that he gave no further thought to CC Sabathia's rough effort on Tuesday night against the A's, and expects that Sabathia will be better on Sunday against the Angels.

Girardi added that even though Sabathia has served up 14 home runs this season, compared to 22 in all of 2012, he believes the left-hander can correct the problem moving forward.

"We're aware of it," Girardi said. "We understand the fastball velocity is not what it used to be, but my thought is, he can still really pitch at a high level. Will he give up more home runs this year than last year? Probably. It would be great if he didn't."

Sabathia allowed six runs on eight hits in six innings in a 6-4 loss in Oakland.

• On this date in 2008, Hideki Matsui became the first Yankee to hit a grand slam on his birthday, in a 4-1 win at Oakland.

Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.