From Comcast SportsNetSAN FRANCISCO (AP) -- San Francisco manager Bruce Bochy plans to start a pair of 16-game winners in the first two games of the National League division series. After that, he says he's not sure what he'll do.Matt Cain will pitch Game 1 against the Cincinnati Reds on Saturday and left-hander Madison Bumgarner will go in Game 2 on Sunday. The two tied for the team lead in victories and were instrumental down the stretch when San Francisco won the NL West for the second time in three years.Two-time Cy Young winner Tim Lincecum and 15-game winner Barry Zito have also been key for the Giants. But Bochy said Thursday he's unsure whether he'll use the two in starting roles or out of the bullpen. That goes for Ryan Vogelsong as well."More than anything it's really vital for us to have all hands on deck here the first two games," Bochy said in explaining his reluctance to name a Game 3 starter. "If we want to use some guys in the rotation early here, then we'll do that. We wanted to keep our options open."The uncertainty over the back end of the rotation might seem strange given that starting pitchers are creatures of habit and generally stay on a carefully mapped out throwing routine in between starts.Zito, who was left off the Giants postseason roster entirely two years ago when the franchise won its first World Series title since 1954, doesn't think that will be an issue.The 34-year-old left-hander has started 172 games and made six relief appearances since signing a 126 million, seven-year contract with San Francisco before the 2007 season."I've (come) out of the bullpen many times as a starter here," Zito said. "A lot of the other guys have done that, too. You change your routine going into it. You can't be stupid about it. Other than that, if you're on the mound you're on the mound."The Giants gathered for a voluntary workout at AT&T Park and players took batting practice while Bumgarner threw a bullpen session as stadium workers hurried to get the stadium ready for Saturday's Game 1. Truckloads of merchandise arrived throughout the afternoon and red, white and blue bunting was hung around the waterfront ballpark.Cincinnati manager Dusty Baker was a surprise visitor to the workout.Baker, the former Giants skipper who recently rejoined the Reds after missing 11 games while recovering from a mini-stroke and irregular heartbeat, stood behind the batting cage and joked with current San Francisco scout Felipe Alou -- who replaced Baker as manager.If Baker hoped to get an insight as to what the Giants plans are for their rotation, he was disappointed.Cain, the NL starter in the All-Star game who earlier this season pitched the first perfect game in franchise history, was an easy call for Game 1. Likewise with Bumgarner, the 23-year-old who was second on the team in ERA, strikeouts and innings pitched."You look at the years that Matt and Madison have had, that's why they're going Game 1 and Game 2," Bochy said. "We feel like these two have earned these starts and that's why they're out there."The rest of the rotation is unclear for various reasons.Zito was one of San Francisco's top pitchers down the stretch to finish with his best season yet since the 2002 AL Cy Young Award joined the Giants. He won his last five starts and seven decisions in the regular season, and hasn't lost since Aug. 2.More critically for San Francisco, the Giants went 11-0 after Aug. 6 with Zito on the mound. That's vastly different from 2010 when he won only one game over the final two months."I'm just happy to be here," Zito said. "Happy to be here, happy to be on the roster, happy to be having fun playing baseball right now. Everything else is gravy."Lincecum, the Giants former ace who lost 10 of his first 13 decisions this season, rebounded well but still finished with a career-high 15 losses.The question for Bochy is whether to keep Lincecum in the rotation or put him the bullpen two years after the right-hander pitched the Giants past the Rangers in the Game 5 World Series clincher at Texas.Vogelsong, 35, would seem the most likely of the three to go to the bullpen. He struggled over the final seven weeks of the season when he had a 6.75 ERA over his final 10 starts."We may use Timmy in the pen, we may use Vogelsong in the pen or Zito," Bochy said. "They'll know exactly what's going on. We'll make sure that they're ready. That's right now what we think is the best way to about it."