ATLANTA -- Cubs left-hander Ted Lilly was scheduled to pitch Friday for Triple-A Iowa, but his session was pushed back to Sunday because of stiffness in his back.

Cubs manager Lou Piniella said the problem isn't serious. Lilly is rehabbing from arthroscopic surgery on his left shoulder, which he had in November. He was to make two more Minor League starts before given the go-ahead to join the Cubs' rotation in mid April.

"This is not a setback," Piniella said of Lilly's back soreness.

The lefty last pitched Sunday in Mesa, Ariz., in the Cubs' Minor League camp, throwing 67 pitches over 5 2/3 innings.

The Cubs also have tweaked their rotation and will have Carlos Zambrano start Saturday rather than lefty Tom Gorzelanny. This was pitching coach Larry Rothschild's original plan, Piniella said, because they wanted to have right-handers face the Milwaukee Brewers next week at Wrigley Field.

Carlos Silva will make his first start for the Cubs on Friday in Cincinnati, followed by Zambrano and then Gorzelanny. Ryan Dempster will get the call for the home opener Monday. He will be followed by Randy Wells and then Zambrano again.

"Then we'll go from there," Piniella said.

Bullpen a work in progress

ATLANTA -- For the past three seasons, Carlos Marmol has been the prime setup pitcher for the Cubs. This season, they're still looking for a replacement.

It isn't easy, as John Grabow found out Wednesday. The left-handed candidate for the job, he served up a game-winning two-run homer to Chipper Jones in the eighth, as the Braves rallied to beat the Cubs, 3-2.

Rookie Esmailin Caridad is the right-handed option, and he pitched one-third of an inning Monday in the season opener. Caridad did not give up an earned run over 14 innings and 12 spring games.

"You're replacing a guy who always has to face the best hitters -- it's always set up that way, whether it's the seventh or eighth innings," Cubs pitching coach Larry Rothschild said.

Marmol, now the Cubs' closer, had yet to get in a game heading into Thursday's series finale against the Braves. Lou Piniella said he wanted the right-hander to see some action to stay sharp. He last pitched Saturday in the final exhibition game in Arizona.

Marmol made 79 relief appearances in 2009 and led the team with 27 holds even though he switched to the the closer duties on Aug. 18. Marmol finished 11-for-11 in save situations.

"The first year he was here [in 2007], he made a big difference and fit right in the seventh and eighth," Rothschild said. "Hopefully, we can replace that."

If needed, Marmol could go two innings in a game. But Piniella doesn't want to do that every day.

"I don't want to get in a situation early in the season where I'm using my closer 1 2/3 [innings] to win a baseball game," Piniella said.

Sean Marshall has been effective against the Braves, striking out seven in 3 1/3 innings over two games.

"To me, he's gotten physically stronger and he had a really, really good spring and good movement on his fastball and a good tight curveball," Piniella said of the lefty, who was among the candidates for a spot in the rotation. "The reason we put him in the bullpen was because I figured that's where we needed him the most. So far, that assumption has been correct. I like the way he's throwing, I really do."

Rookie James Russell also pitched two scoreless innings on Monday. The debuts for both Jeff Samardzija and Justin Berg on Monday weren't as smooth. Piniella and his staff are still getting to know the pitchers.

What they needed more than anything before leaving the state of Georgia was a win.

"[If you're] 2-0, you're on top of the world, and 0-2, you're six-feet under," Piniella said. "It's early. We've got to sort some things out there.

"It's early in the season and we're going to be fine," he said. "Winning that first ballgame is important."

Silva eager to get to work for Cubs

ATLANTA -- Carlos Silva can't wait for Friday when he'll make his Cubs debut against the Reds.

"I'm very excited," Silva said Thursday. "I'm looking forward to starting my first game and hopefully pitch the way I pitched in spring."

After going 5-18 the past two seasons with the Mariners, Silva said his goal this spring was to be consistent.

Mission accomplished.

"It wasn't one good game, one bad game," Silva said. "That's what I'm looking for in the season -- is try to be consistent on the mound."

Well, he did that after a rough first start. On March 6 against the White Sox, Silva's first spring start, he gave up six runs on seven hits, including two home runs by White Sox slugger Carlos Quentin, over two innings.

"After you have two bad seasons and then the first game, you have that kind of game, you think, 'Oh my God, here I go again,'" Silva said. "I've been working very hard to stay very strong in my mind. I tried to put that game away and keep working and keep learning and try to improve."

Pitching coach Larry Rothschild has made some changes with Silva's mechanics that have helped. But Silva feels better mentally, too.

"It's not only Larry but the whole coaching staff -- the way they've been talking to me," Silva said. "They have a lot of trust in me, and that gives me a lot of confidence. Larry will tell me before a game, 'Trust yourself, let it go and throw the same way you do in the bullpen.' That's what I try to do."

Best of all, Silva's wife and his mother will be in Cincinnati for the game. His mother got a 10-year visa and joined the Silvas in Arizona this spring. Home cooking helps, too.