PHOENIX -- Last year at this time, Zach Jackson was a newcomer to the Brewers who quietly dressed at a corner locker. Carlos Villanueva was entering his third season with the club but his first in big-league camp, and just tried to stay out of the way.

"You have to be as unnoticeable as possible," Villanueva said. "I had never played above high-A."

And now?

"It's like night and day," Jackson said.

"I know all of the guys here," Villanueva said. "Not to sound overconfident, but you don't have to be hesitant to say something. The biggest thing now is that I feel like I'm a part of the team. I feel like I'm part of what we're trying to do here."

Both 23-year-old pitchers -- Jackson a left-hander and Villanueva a right-hander -- made their Brewers debuts last summer and finally helped stabilize a Brewers pitching staff that was reeling from injuries to Tomo Ohka and Ben Sheets.

Both made quite a positive impression, especially Villanueva, who went 2-2 with a 3.69 ERA in 10 games, six of them starts. Jackson also saw some success, going 2-2 with a 5.40 ERA in eight games, seven starts.

Villanueva will be in the mix for a bullpen spot this spring, but there is a chance both will end up in Triple-A Nashville's starting rotation. But the duo, plus right-handed super-prospect Yovani Gallardo, will be the first line of defense should the Brewers run into more problems with their starting rotation.

"It's kind of a luxury because for the first time we have a little depth in that area," Brewers pitching coach Mike Maddux said. "In springs past, we looked for guys that could fill the role. Now we have guys competing for roles. That's a good thing to have."

Acquired in a trade with the Giants at the end of 2004 Spring Training, Villanueva made three stops in 2006, beginning at Double-A Huntsville, where he posted decent numbers: 4-5 with a 3.75 ERA in 11 games. The Brewers, meanwhile, had tried callups like Ben Hendrickson and Dana Eveland in Sheets' and Ohka's spots without success, and desperately needed to stabilize the staff. The team took a chance on Villanueva.

He responded, making three separate trips to Milwaukee and dominating for Triple-A Nashville in-between to the tune of a 7-1 record and a 2.71 ERA. With the Brewers, he limited opponents to a .216 batting average.

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"So many things happened in one year," said Villanueva. "It was definitely a breakthrough. It was a chance to show that I belong here. No matter what happens now, I'm here to make the team. That's my No. 1 goal."

But the Brewers have five experienced starters expected to fill the starting rotation: Dave Bush, Chris Capuano, Ben Sheets, Jeff Suppan and Claudio Vargas. Villanueva says he is more than willing to take a bullpen role.

"You have to be realistic -- we both know exactly what's going on," Villanueva said. "But at the same time, you have to go out there and compete. Like last year, I knew I had no chance of making the team, but I still treated every outing like I was competing for it."

So did Jackson, who was acquired along with Bush and outfielder Gabe Gross in a 2005 Winter Meetings trade that sent popular first baseman Lyle Overbay to the Blue Jays. Jackson was a supplemental first-round draft pick of the Jays in 2004, and he was rated Toronto's eighth-best prospect by Baseball America before the trade.

Jackson started 2006 at Nashville, where he went 2-2 with a 3.00 ERA before joining the Brewers on June 3. At that time, he had pitched only 41 games as a pro.

"There was never a moment where I was intimidated, where I felt like those guys were that much better than me," Jackson said. "I caught a hot team when I faced the Twins [on July 2], and that was my worst outing. But for the most part, I kept us in games, and I'm proud of that. That's our job."

Jackson said he worked with some of his college coaches on a few minor adjustments during the offseason, related to getting his front foot down more quickly and not "flying off" during his delivery. He'll continue to work this spring on his changeup, and he tweaked his slider during the offseason so it has more depth and downward break. Before, Jackson's slider was too similar to his cut fastball.

"The average fan is still going to see how Zach still goes over his head [during his delivery] and has that quirky motion," Jackson said. "My changes have been a little more specific. I want to limit the walks and all the other little things that add up.

"I just want to be ready in case something comes up and there is an opportunity. Our rotation is pretty much set, so I just have to take care of the things I can control, and that's getting prepared."

Villanueva is not working on any new pitches this spring ("Thank God my changeup never leaves me," he says) but he does have a bit of a new look. He dropped about 15 pounds during offseason workouts in the Dominican Republic with Brewers closer Francisco Cordero. By the end of last year, probably the result of clubhouse spreads and 2 a.m. hotel room service, Villanueva figures, he had bulked up to 233 pounds.

"I felt good, but I saw some of the games and I didn't look good," he said. "I looked overweight."

Where they go in 2007 remains to be seen, but it's possible that Jackson and Villanueva will both see some action in Milwaukee.

"It helps to have guys you can talk to, to get things off your chest when you need to," Villanueva said. "We're really looking forward to this year, even more than last year."