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03/14/2013 8:03 PM ET

Weeks returns to A's unsettled second-base battle

PHOENIX -- Oakland's roster remains largely unsettled just 17 days before it must be finalized.

More specifically, the club has yet to identify its middle-infield starters up to this point, and those decisions might even carry into April, manager Bob Melvin said Thursday.

There are almost too many contenders at second base, and the leading competition between Jemile Weeks and Scott Sizemore has seemingly been a bust. Weeks lost two weeks to a shoulder injury and will be in the starting lineup Friday for the first time since March 1. Sizemore, meanwhile, is hitting just .125 after going 0-for-3 with two strikeouts and stranding seven men on base in Thursday's 6-2 loss to the Rangers.

Typically, teams don't put too much stock into spring performances, but the A's have no choice but to do so this year, with so many question marks surrounding their roster.

Jed Lowrie, then, could ultimately appear in the Opening Day lineup at second base, should the A's not feel comfortable with Weeks or Sizemore by then. Lowrie is having a dynamic spring, batting .375 with two home runs and nine RBIs for his new team.

But could Lowrie also be needed at shortstop? It's possible, since the A's don't yet appear to be sold on Japanese infielder Hiroyuki Nakajima, who has simply proved to be subpar on both defense and at the plate.

Melvin, it seems, is only certain of one thing.

"Certainly Jed Lowrie is a guy that we're going to have to find a spot for him somewhere the way he's playing now," Melvin said. " He's certainly making a case for himself to be in there somewhere. Whether that's every day at a position or moving around, which you've seen him do here in spring, that's still open for debate, too."

For the four infield spots, the A's are likely to carry six bodies. Josh Donaldson is expected to start at third base, with Brandon Moss manning first. That leaves four spots for these five: Nakajima, Lowrie, Weeks, Sizemore and Adam Rosales, a mix that doesn't even include other options Eric Sogard and Andy Parrino. In the end, it's likely going to be Weeks or Sizemore who is sent down to start the year at Triple-A.

Melvin, of course, isn't ready to have those discussions, though, with a little more than two weeks still on his side.

"Even maybe when we get [the season] started, we're not sure the exact formula where everybody goes," he said. "We're pretty consistent in saying we're going to take a good hard look at everyone.

"The one thing we will know, at the end of spring, we'll be down to 25 guys."

Comfort level eluding Nakajima in first spring foray

PHOENIX -- On a day when he made a pair of wayward throws, one which resulted in an error, A's shortstop Hiroyuki Nakajima stood at his locker and expressed confidence in his defensive progression. It's his offensive game that's lagging, he believes.

"I've been wondering and thinking," Nakajima said. "I'm definitely not at the comfort level I was in Japan."

The infielder believes that will come with time, but there's not much of it before the regular season begins, and it's unknown whether the A's are intent on sticking with him on an everyday basis when it does.

"More experience will help me understand the flow of the game better," Nakajima said. "I want to make those necessary adjustments while learning from these experiences."

Through 11 spring games, Nakajima is 6-for-25 (.240) with 10 strikeouts and just one extra-base hit. His on-base percentage, manager Bob Melvin noted, is much higher at .387, the result of three walks and three hit-by-pitches. But Nakajima is here to hit.

"Right now, there's always that slight-second pause in my mind," the shortstop said. "Everything's not flowing naturally right now, because of that split-second thought. If I can eradicate that, I think I can live up to my potential and get to that comfort level where I want to be at the plate."

"It looks like he's drifting a little bit," Melvin said. "Some of the video we've seen, he's on his back leg a little more. But you know what? There are a lot of things he's dealing with right now. When you don't get off to the type of start that maybe you would like, swinging the bat, it's tough, because he wants to make a good impression right away."

As for his defense, particularly what was on display Thursday, he believes it was simply out of character, especially since he felt so at ease during the morning's drills.

"I admit that I wasn't well-balanced while I was fielding today," Nakajima said. "The first time I thought I threw a bullet, but then it went way up. The second time, I tried to control it, but then it went into the ground. It was just kind of, overall, an unbalanced day."

"We haven't seen a whole lot of that," Melvin said.

Rodriguez has torn UCL; Tommy John surgery next?

PHOENIX -- Fernando Rodriguez had just enough time to get to know his new teammates before learning that he won't be joining them on the field for quite some time.

The right-handed reliever, acquired by the A's just last month with Jed Lowrie from Houston, learned Wednesday that he has a torn ulnar collateral ligament in his pitching elbow and is likely headed for Tommy John surgery.

First, though, Rodriguez will get a second opinion before committing to the operation, which typically calls for a year's worth of recovery time.

The 28-year-old pitcher initially experienced elbow soreness in Monday's game against the Padres. He made just seven pitches before departing with a trainer, which led to a visit with associate team orthopedist Dr. Will Workman.

Workman discovered the UCL damage via MRI results and recommended Tommy John surgery, normally the standard route to take with such an injury. But manager Bob Melvin said Rodriguez and his agent planned to seek another doctor to "talk about what the next course of action might be."

Rodriguez's chances of making the team out of camp were slim, considering the bullpen is already crowded with proven arms. The righty made 71 appearances for the Astros in 2012, pitching to the tune of a 5.37 ERA with 78 strikeouts in 70 1/3 innings.

Worth noting

• Left-hander Brett Anderson, who suffered a minor neck injury in his last outing, is on track to make his scheduled start Saturday, but it will likely come in a Minor League game, rather than against the Angels at Phoenix Municipal Stadium.

"He won't pitch against the division," Melvin said, "and we can get his pitch count where we want to get it."

Anderson, already pegged as the A's Opening Day starter, threw just seven pitches in his last start, his third of the spring. He'll throw close to 60 on Saturday.

• Closer Grant Balfour, on the mend from minor knee surgery, will throw to hitters for a second time on Thursday, as the A's attempt to keep him on the same schedule every other pitcher employed early in camp. The team will then decide if the right-hander is ready to pitch in games.

• Outfielder Michael Taylor, sidelined for over a week following a freak injury to his right pinky finger, was back on the field Thursday as a late-inning replacement. He went 1-for-2.

The 6-foot-5 Taylor hit his hand on a light on the ceiling of the dugout as he attempted to toss his gum into the trash, resulting in a deep cut on his pinky.

• Non-roster reliever Mike Ekstrom has quietly been a nice surprise for the A's this spring. The right-hander pitched two perfect innings in Thursday's game, and overall, has compiled a 2.08 ERA with seven strikeouts and just four hits allowed in 8 2/3 innings.

Ekstrom is likely to start the year at Triple-A Sacramento, but could be a nice weapon for the A's down the line.

"He's got a good, tight slider, throws the ball over the plate, keeps the ball down," Melvin said. "There's something to be said for that. He's had a nice spring."

Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.