MESA, Ariz. -- Cubs manager Lou Piniella has a few things he's looking for this spring when Cactus League games begin on Wednesday.

With Mark DeRosa gone, the Cubs need to find a backup third baseman. Luis Rivas, a non-roster invitee who has played for Minnesota, Cleveland and Pittsburgh, was working out with the regulars on Tuesday and will get a good look.

"If our scouts are looking for anything at all this spring, that's one thing we're looking for," Piniella said of a backup infielder who can play the left side.

Because Geovany Soto will be leaving Sunday to play in the World Baseball Classic, Paul Bako and Koyie Hill will get most of the playing time behind the plate as the Cubs try to determine the best backup catcher.

Outfielders like Richie Robnett, Joey Gathright, Sam Fuld and Brad Snyder should get plenty of at-bats as well.

Piniella will have Soto, Derrek Lee, Mike Fontenot and Ryan Theriot start on Wednesday in the Cactus League opener against the Los Angeles Dodgers. Aramis Ramirez, Alfonso Soriano, Reed Johnson and Milton Bradley will start on Thursday against the Milwaukee Brewers. Both games will be played at HoHoKam Park.

Ted Lilly, who will be pitching for Team USA in the World Baseball Classic, will start Friday against Texas in Surprise, and then leave for Florida to train.

Some of the starting pitchers are being held back. Rich Harden isn't ready for games yet and Carlos Zambrano is scheduled to start Monday against Arizona. Ryan Dempster was to meet with pitching coach Larry Rothschild on Tuesday to determine when he will be slotted into the Cactus League rotation. Dempster has been facing hitters during early throwing sessions.

"I don't think I'm behind schedule," Dempster said. "I know my body pretty good."

Jeff Samardzija, who would like to be considered for the vacancy in the rotation, and Mitch Atkins, who won 17 games last season combined at Double-A and Triple-A, will each pitch two innings on Wednesday in the opener.

"We'll get a chance to see our young pitching here a lot," Piniella said. "The ones who do well will get a lot of playing time."

That will include pitchers such as Kevin Hart, 26, who is hoping to lock up a spot in the bullpen, as well as veterans like Chad Fox, who want to prove they can still compete.

"I think last year was the exact same situation [as this year]," Hart said. "There were four of us who were competing for one spot. This year, I feel it's the same situation."

The right-hander was 4-2 with a 2.81 ERA in 26 games at Triple-A Iowa and compiled a 6.51 ERA in 21 games with the big league team. The difference in those numbers resulted in a long winter for Hart.

"On the Minor League side, it was great," he said. "There were times on the Major League side it was good, but I don't think the consistency was there last year. It's something that ate at me over the winter. I'd be worried if that didn't bother me. You feel like you're a lot better than what you showed, and that's the frustrating part."

Fox's career has been slowed because of his right elbow. The 38-year-old right-hander appeared in three games in relief with the Cubs last season before he had to be shutdown.

"We do have a lot of games and in a sense that's good, because for me it gives me more chances to go out there and they can say, 'Hey, wait a sec, he can do it,'" Fox said.

So far this spring, Fox has felt strong. He's not asking for the radar-gun readings.

"I go off the hitters' reactions, and talking to Derrek Lee and the guys I've faced, they seem really happy for me the way the ball's coming out of my hand," Fox said. "This year, I feel a little more relaxed, a little more free and easy, a little more, this is like old times. Last year, it was such a big question mark. This year it is, too, but last year, I felt like every pitch was under the microscope. This year, I feel I can get back."