SAN DIEGO -- After catching nine innings on Opening Day, Buster Posey started at first base in Friday night's game against the Padres, a sign of the Giants' desire to slowly ease their franchise star into action as he comes off major hip surgery. 

Posey did not catch back-to-back nine-inning games during Spring Training, but manager Bruce Bochy said he's been cleared to do so. The Giants plan to start Posey behind the plate again Saturday before giving him a day off in Sunday's series finale at Petco Park. 

"He's fine to go back to back," Bochy said. "He's done it already. This is just a way to kind of break him in in the early go here. But he said after [Thursday's] game, he's good with whatever we want to do."  

The decision to place Posey at first base meant Brandon Belt was out of the starting lineup against Padres left-hander Joey Lucchesi. Bochy acknowledged that Belt might not start as many games as he normally would in the first couple of weeks of the season to accommodate Posey. Though the Giants didn't play Belt in the outfield during Spring Training, Bochy said left field remains an option for the 30-year-old veteran. 

"I think he understands that Buster will be playing some first, especially against certain left-handers," Bochy said. "But Belt is our first baseman. And I don't want it to come across like he's going to be platooned. He's not. He's going to be playing first tomorrow against a left-hander. The plan was to give the guys three out of four here. We'll try to stick with it. And I think it's fair to say that if it's easier to keep Buster in the lineup, he's going to mix in a few more games at first."  

Erik Kratz, whom the Giants acquired Saturday to serve as Posey's backup, made his first start at catcher Friday. While he's been with the club for less than a week, Bochy expressed confidence in Kratz's ability to learn the pitching staff on the fly. 

"He studies the game," Bochy said. "He's been down in the bullpen catching guys. Even the first day we got him, he knew he wasn't going to play. He said, 'I'm going to hustle out there and catch some of the guys in the bullpen.' It'll be an easy adjustment because of his experience."  

While Kratz also has five relief appearances under his belt, Bochy said Pablo Sandoval remains his first choice if he needs a position player to pitch. 

"He's still No. 1," Bochy said. "I think you look at the job he did, it's pretty impressive. I couldn't do that to him."  

Lineup shuffle 

After being shut out Thursday, Bochy promised to mix up the Giants' lineup for their second game of the season. Sure enough, Friday's lineup looked quite different, with Michael Reed batting leadoff, Posey at first and Belt and Joe Panik sitting against Lucchesi. Yangervis Solarte, a switch-hitter, started at second base in place of Panik. 

Bochy said the changes were partly a result of his desire to keep his starters well rested at the outset of the season and to see which configuration clicks best against left-handed pitching.  

"I think you'll see us mix it up pretty good," Bochy said. "We have some versatility with some guys. As always, you look at the pitcher and try to get the best matchups you can. But to add to that, in the early go here, the plan was to play a lot of the core guys three out of the four [games] just to get their legs underneath them and not wear them down in the early go."  

Worth noting

The Giants traded catcher Tom Murphy to the Mariners in exchange for Minor League right-hander Jesus Ozoria on Friday. The Giants claimed Murphy off waivers from the Rockies earlier this week, but they designated him for assignment Thursday after electing not to carry him on their Opening Day roster. Ozoria, 20, logged a 2.19 ERA over 49 1/3 innings in Rookie-level ball last year. He struck out 59 while walking only seven and also posted a 39.3 percent ground-ball rate.