MESA, Ariz. -- Cubs first baseman Bryan LaHair was held out of physical activities Tuesday because of continued tightness in his lower back, and he'll be re-evaluated on Wednesday as to his status for the club's season opener, manager Dale Sveum said.

Sveum said that LaHair's injury, which has held him out since Friday, isn't serious enough to merit DL talk, and he expects the left-handed hitting LaHair back by the weekend. The Cubs open the season Thursday against Washington before an off-day Friday.

"We'll see what happens on opening day," Sveum said. "He's getting better every day, so we'll just see with the treatment and everything, but he won't be doing anything today. We'll see what happens tomorrow."

The 29-year-old LaHair used a strong finish to piece together a very nice spring for the Cubs, hitting .295 with a .410 slugging percentage -- though he didn't hit any home runs.

He clubbed 38 homers with Triple-A Iowa last year to go along with two more and a .288 batting average in 59 at-bats at the big league level.

Sveum said LaHair's range of motion is fine, but he'll have to overcome a shooting pain in his back. Asked if it would require some sort of evaluation in the form of an MRI, Sveum didn't seem too concerned.

"Once you've played for a long time, pretty much everybody's MRI will show something or some sort of a bulging disc, whether it's big or small," Sveum said.

Sveum wants Castillo to build up strength, velocity

MESA, Ariz. -- Manager Dale Sveum said Monday that decisions regarding the Cubs' bullpen will come down to the 11th hour.

Perhaps the most intriguing of those 11th-hour arms is 22-year-old righty Lendy Castillo, whom the club selected from the Phillies in the Rule 5 Draft. He completed his spring on Monday with a shaky, but scoreless inning, and on Tuesday Sveum said he still isn't certain about the state of his pen.

The Cubs only hope to retain Castillo would be keeping him with the big league team, though doing so would mean Castillo is making the jump from Class A to the Majors.

"He's done OK," manager Dale Sveum said before club's final spring training game on Tuesday. "The velocity isn't quite what it was earlier in camp. But he's been pitching a lot more than he probably ever has. That's one thing we've had to eyeball. He had to get built up. If he's going to be in that role, he's going to have to pitch quite a bit."

And he has pitched quite a bit in the Cactus League, appearing in more games -- 11 -- than any other Cubs pitcher. With a shaky, but scoreless ninth on Monday Castillo finished the spring with a 3.46 ERA in 13 innings pitched. He's had some control problems, walking 13 hitters.

Castillo last pitched with Philadelphia's Class A club, Lakewood in the South Atlantic League. A converted shortstop, Castillo has never appeared in more than 21 games in a season. In 2010 he was used primarily as a starter, where he threw 65 innings, and in 2011 Castillo logged 46 innings, mostly out of the bullpen.

"In the National League, you can't have a guy that's non-usable, so, he's got to be built up to where he could pitch three innings, get to 50-60 pitches once in a while," Sveum said. "He's not the biggest framed guy in the world to put a workload on, but he's got to get used to it."

Worth noting

• Sveum expects Year 3 to be a breakout year for Starlin Castro. He says he was very impressed this spring with the way Castro challenged himself.

"He's had that time to mature defensively, to mature on the mental side of the game," Sveum said. "I think everybody gets to the point where you've played enough baseball and then OK now you've got enough Major League Baseball to where things start improving."

• Sveum said the club will bring all of its remaining big league players to Chicago before any decisions are made on the make up of the bullpen. As for if Sveum thinks the team will go after an outside arm: "There's always a possibility, but it's just like everybody else. There's a lot of bullpens that will be 11th-hour decisions."

• Dale Sveum is expecting that the veteran presence of Matt Garza will help the club, saying, "The guy has pitched in a World Series and he's done well. The numbers last year were pretty good on a not-so-good-team." Garza will get the ball Saturday against Washington.