Chicago Cubs manager Lou Piniella made it official on Saturday -- rookie right-hander Justin Berg has made the pitching staff to start the 2010 season. Piniella said there’s still a battle for the last bullpen spot between left-handers John Gaub, James Russell and Marcos Mateo, as well as right-hander Mike Parisi.

Parisi was a Rule 5 acquisition. If he doesn’t make the team, he has to be offered back to the St. Louis Cardinals for the waiver price.

Fuld vs. Colvin: The Cubs are leaning toward keeping a defensive outfield specialist for their Opening Day roster. It appears it will come down to a battle between Sam Fuld and Tyler Colvin.

Colvin has been the team’s hottest hitter this spring, however, there’s some in the organization that aren’t convinced he can handle center field for any extended period of time.

Fuld is a wizard at handling all three outfield positions and also adds a little more speed to the bench if he makes the team.

Millar vs. Tracy: Veterans Kevin Millar and Chad Tracy are both trying to make the 25-man roster. For Piniella and his staff, it’s a difficult choice to make. Piniella was asked if both could possibly make the team.

“It’s hard,” Piniella said. “I’m not saying it’s not possible. We like both players a lot. There’s a lot to say about contributions and leadership from your veterans.”

The rotation: Piniella and pitching coach Larry Rothschild have mapped out an Opening Day plan where the starters will get three starts apiece in April. After that, the Cubs are hoping that rehabbing left-hander Ted Lilly will be able to return to the rotation.

The leaders for the fourth and fifth spots appear to be left-hander Tom Gorzelanny and righty Carlos Silva. Piniella said he’ll make a decision on the rotation by March 24.