OAK@LAA: Sizemore injures knee, leaves game in fourth

OAKLAND -- Second baseman Scott Sizemore underwent successful surgery to repair the ACL in his left knee, the A's announced on Tuesday.

Dr James Andrews, who performed the surgery in Florida, used a patellar tendon graft to reconstruct the ACL -- a hamstring tendon graft was used during the same surgery last year -- and also repaired the meniscus.

Of the operation, Oakland manager Bob Melvin called it "very successful."

Sizemore is resting comfortably in Florida, according to the club, and will return to the Bay Area on Saturday to begin rehab. As expected, he will miss the rest of the season, after sitting out all of 2012 with the same injury.

The 28-year-old infielder was playing in just his second game of the season last week in Anaheim when he suffered the ACL tear.

With Moss on paternity leave, Peterson makes debut

HOU@OAK: Peterson's diving grab gets A's out of third

OAKLAND -- The hot-hitting Brandon Moss will miss the remainder of the Astros series after becoming a parent for the second time on Tuesday.

While Moss attends to his wife, Allison, and new son Brody Dylan -- who weighed in at seven pounds and nine ounces -- the A's will get a look at Shane Peterson, who made his Major League debut at first base on Tuesday following his callup from Triple-A Sacramento when Moss was placed on the paternity list.

That's where Moss -- hitting .283 with a team-leading 13 RBIs -- must remain at least one day but no more than three days, and manager Bob Melvin said the club is expecting him to make the charter flight to Tampa on Thursday's off-day in preparation for the team's weekend series against the Rays.

In the meantime, Peterson, 25, hopes to make the same kind of impression on the big league folk that he did in Spring Training last month, when he compiled a .408 average. In 11 games with Sacramento, he was batting .410 with five doubles and seven RBIs.

"I feel good," Peterson said. "I tried to make sure I was ready to go in Spring Training. I didn't want to use that as an opportunity to get ready. I wanted to already be ready, and I'm just trying to have the same success I had there and carry that into the regular season."

While he went 0-for-4 in his big league debut, Peterson contributed with a key defensive play, robbing Houston's Rick Ankiel of a bases-loaded hit with a diving catch to end the top of the third inning in the A's 4-3 win.

"To come up huge in that situation, to make that play, that's the play of the game right there, not to take anything away from [Josh] Donaldson's [go-ahead RBI] triple [in the eighth inning]," starter A.J. Griffin said. "But that play's huge, kept us in the game and allowed me to keep going."

Peterson, was with the A's less than two weeks ago in Houston, but only because of a false alarm, with Moss back in the Bay Area when his wife went into labor early. Moss returned the next day, and Peterson was never placed on the active roster.

His parents, Southern California natives Brad and Sue, were in Houston in the event their son got an opportunity to play, and they made the seven-hour drive on Tuesday from Temecula, Calif., near San Diego, to see that happen.

"Obviously last time I was up here, I was hoping to get an opportunity and things didn't work out, so I'm just excited to be back again," said Peterson, who has more than 500 Minor League games under his belt. "I'm trying to go out there and not do too much, not get too excited or too amped up and just keep doing what I've been doing the last couple of weeks.

"For me right now, I'm just trying to soak it all in and make sure that this is a great experience. A lot of people don't get this opportunity, so I'm just trying to be thankful for that and go out there and do the best I can and play the type of baseball I've been playing all my life."

Peterson has played almost exclusively in the outfield the past two years in the Oakland organization, appearing at first base just one time last year and again on Monday. But it's his natural position and he's been taking plenty ground balls there in the past few weeks in anticipation of a potential promotion.

"This is everybody's dream," Peterson said. "If it would have taken me 500 games, five games, 5,000 games, whatever it is, it means a lot to be here and get this opportunity. Who knows how long it's going to be, but that's something I try not to worry about."

A's play 'Sweet Caroline' to honor marathon victims

HOU@OAK: A's sing "Sweet Caroline" for Boston

OAKLAND -- The A's played "Sweet Caroline" in the middle of the eighth inning during Tuesday's game against the Astros to honor the victims of Monday's Boston Marathon tragedy.

The Fenway Park theme -- played in the middle of the eighth inning at Red Sox home games -- was heard across several ballparks at different times on Tuesday, with Oakland joining in, too, while also lowering its flag at the Coliseum to half-staff.

The phrase "Tonight, we are all Bostonians" was shown on the Coliseum video screen while "Sweet Caroline" played.

The A's also paid tribute to the victims the night before, offering a moment of silence before Monday's game to all those affected by the day's horrific events, which left three people dead and more than 170 injured.

Oakland will pay a visit to Fenway come Monday for the opener of a three-game series with the Red Sox.

Worth noting

• Adam Rosales (intercostal strain) will begin a rehab assignment with Class A Stockton in San Jose on Wednesday.

• The A's will use Thursday's off-day to give each of their starters an extra day of rest. That means Brett Anderson will be on the mound for Friday's opener in St. Petersburg against the Rays, with Jarrod Parker and Tommy Milone to follow in the three-game series.