PEORIA, Ariz. -- The Cubs' pitching is falling into place, with Sean Marshall being named the fifth starter on Thursday and Aaron Heilman moving into the bullpen.

Cubs manager Lou Piniella made the announcement after a 9-2 win Thursday over the Seattle Mariners. Piniella wanted to talk to Heilman, who started the game, before he made it official.

"I told him he did an outstanding job and that we were going to put Marshall in the fifth spot," Piniella said of his conversation with Heilman, who gave up four hits and one walk over 3 2/3 innings against the Mariners.

"He was fine with it, and he said he would help in any way he could," Piniella said. "I told him he was throwing really well. We gave him a chance to use all his pitches, build up his arm strength, and now we're going to put him in that specific role."

Earlier Thursday, Piniella had called Jeff Samardzija into his office to let the right-hander know he's still got a chance to make the Opening Day roster as a reliever, too. Samardzija isn't alone in the competition.

Here's what we now know: the Cubs will carry 12 pitchers, and that includes starters Carlos Zambrano, Ryan Dempster, Ted Lilly, Rich Harden and Marshall. Piniella said five other pitchers have secured spots in the bullpen. He did not want to name the quintet, but that list obviously includes Heilman, Kevin Gregg, Carlos Marmol, Neal Cotts and one player to be named.

There also are two openings to be filled.

Samardzija had been one of the candidates for the rotation along with Marshall, Heilman and Chad Gaudin. Marshall has stood out among the others, giving up one earned run on nine hits and striking out eight over 14 1/3 innings in his five spring outings.

"Marshall came in here as the front-runner for the fifth spot," Piniella said, "and he's done nothing to lead me to believe he's going to lose that spot."

There has been some consideration to send Samardzija to Triple-A Iowa so he could start and stay stretched out. Last season, the right-hander pitched well out of the 'pen when he was called up to the Cubs, compiling a 2.26 ERA in 26 games.

"[Samardzija] will be given every chance for a bullpen job, and it's up to him to grab it," Piniella said. "We're going to leave with the best pitching staff that we can here."

Besides Gaudin, the list of relief candidates also includes Rule 5 Draft pick David Patton, who has a 1.17 ERA in seven games, and Randy Wells, who gave up his first run this spring in six innings over six outings on Thursday.

"He's impressive," Piniella said of Patton, who has not pitched above the Class A level. "We're not pitching him early in the ballgame, we're pitching him later in the ballgame with leads to see how he responds, and he's throwing strikes and showing a lot of composure for a kid who just pitched in 'A' ball last year. It's very nice to see. I'll tell you this, he's in the picture."