TEMPE, Ariz. -- Cubs first baseman Bryan LaHair has not played for two days because his back tightened up, possibly from his long commute in Arizona, but is expected to be ready for Opening Day.

"He said, 'I could've played today,'" Cubs manager Dale Sveum said Sunday. "Backs are like that."

LaHair, who is batting .295 this spring with no home runs, was in the early lineup posted on Saturday for Sunday's game against the Angels in Tempe. But on Sunday, Blake DeWitt started at first base and LaHair received treatment for his back. What happened?

"I don't know," LaHair said on Sunday in Mesa, Ariz. "I have a [one]-hour ride to the field and back every day, and sitting in that one position, it tightened up a little bit. It's no big deal."

LaHair said he hoped to play on Monday or Tuesday, when the Cubs will play their final Cactus League games in Arizona. He expected to be ready for the season opener on Thursday against the Nationals at Wrigley Field.

The first baseman, who belted 38 home runs last year for Triple-A Iowa, has yet to connect this spring. Sveum said he wasn't worried about LaHair's performance.

"People forget that home runs come in bunches, and you need 600 at-bats to hit 25 to 35 home runs," Sveum said. "He's hitting plenty of balls off the wall. The day he went down [to the Minor League camp] and got seven at-bats, he hit three balls off the wall. Home runs aren't as important to drive runs in as slugging percentage is. Slugging percentage is the key."

So far, LaHair has seven doubles and a .410 slugging percentage this spring.

Marmol hitting stride as opener approaches

TEMPE, Ariz. -- Carlos Marmol did not allow a baserunner on Saturday and has shown better command of his pitches. It's good timing for the Cubs closer.

"His last few outings, his slider is definitely crisp," Cubs manager Dale Sveum said Sunday of the right-hander. "More importantly is the fastball. He's gotten ahead with it or gotten back in the count with it.

"He's staying away from two-ball counts or 3-1 counts and putting himself in a situation where if he goes 1-0, he gets back in the count with a fastball and then can throw his slider. He's feeling a lot better with the new fastball grip."

In his last six outings, Marmol has given up two hits and walked three while striking out four. Sveum will likely use Marmol for one inning during the season, maybe four outs if needed.

"Winning the game is most important, obviously, but in the scheme of things, the least amount of pitches we can get these guys to throw the better," Sveum said. "If he's going into games and having quick innings without 20 to 30 pitch innings, yeah, we can use him for four outs.

"There will be those nights when Kerry Wood might be off and [Marmol] has had his rest and he has a day off the next day -- all those kind of things come into play when you're dealing with the bullpen and using the closer for four, five outs."

Cubs waiting until 11th hour to set bullpen

TEMPE, Ariz. -- The Cubs have eight relief pitchers in camp, but they have only seven spots available and most likely won't make a final decision until Wednesday, when 25-man rosters need to be set.

"I wouldn't say we're any closer, no [to a decision]," Cubs manager Dale Sveum said on Sunday. "There are still performances to be done."

The Cubs have Cactus League games Monday and Tuesday before breaking camp to head to Chicago for Thursday's season opener against the Nationals.

The eight pitchers include Carlos Marmol, Kerry Wood and James Russell, who are set. Rodrigo Lopez appears to be the leader for the role as long man. Others still competing include Manuel Corpas, Rule 5 Draft pick Lendy Castillo, Rafael Dolis and recently acquired Shawn Camp. Camp gave up one hit and struck out three over 1 2/3 innings on Sunday against the Angels.

Lopez gave up three hits and walked two over two innings on Saturday against the Angels, striking out three.

"I don't think he was as sharp as he could've been, but then he found it and made the pitches he was trying to make to get out of it," Sveum said of the right-hander. "To get into the mess, he was off, and then he made the pitches he had to. That's kind of what he's always been capable of doing, and I think that's what keeps him around. He's a guy who never has overpowering stuff, but one of those guys who finds a way to make the pitches when he has to. That's always a good sign."

Extra bases

• Matt Garza, the Cubs' No. 2 starter, tuned up for the season on Sunday with four innings in a Minor League game at Fitch Park in Mesa.

Garza gave up two hits and struck out six, throwing 51 pitches. He then went to the bullpen to throw some more. The right-hander's next start will be Saturday against the Nationals at Wrigley Field.

• Alfonso Soriano batted fourth on Sunday and Sveum said he may keep the left fielder there and put LaHair in the No. 5 spot. It's an option.

"Toying with it is a good word," Sveum said of his lineup.

• Ian Stewart will make his first Opening Day start with the Cubs on Thursday, ending Aramis Ramirez's eight-year run at third base. Trivia question: Who started at third in 2003 before Ramirez's arrival? Mark Bellhorn.

Stewart also will celebrate his 27th birthday on Thursday. Only two Cubs players have celebrated a birthday by playing on Opening Day. Ross Barnes did so on May 8, 1877, when he turned 27. He went 2-for-4 and scored twice. On April 2, 2001, Jon Lieber took the loss on his 31st birthday, a 5-4 decision to the Expos.

Thursday also is backup catcher Steve Clevenger's birthday. He'll be 26.