HOUSTON -- Having affirmed that Buster Posey will be in the lineup frequently, manager Bruce Bochy highlighted that issue again Thursday by outlining the Giants' plans for using the rookie to catch.

Posey has played primarily first base since being recalled by the Giants despite being considered the club's catcher of the future. He started at first base Thursday as his two-game absence from the lineup ended.

But Bochy said that Posey, who has started only one game behind the plate for San Francisco, will catch "at least once a week, if not once through the [pitching] rotation." That plan will go into effect Saturday, when Posey is expected to form San Francisco's battery with right-hander Joe Martinez aganist the Boston Red Sox.

Bochy reiterated that Posey has been trying to sharpen his receiving skills by catching the starters' between-starts bullpen sessions and performing drills.

Torres, Sandoval sit against lefty

HOUSTON -- Bound to alter the Giants' lineup for a day game following a night game, manager Bruce Bochy played percentages and rested Andres Torres and Pablo Sandoval in Thursday's series finale against the Houston Astros.

Left-hander Wandy Rodriguez was due to start for Houston, which would have forced switch-hitters Torres and Sandoval to bat from their weaker sides. Torres entered Thursday hitting .284 overall, including .220 right-handed and .309 left-handed. Sandoval, a .276 hitter, was batting .229 right-handed and .293 left-handed.

Bochy also noted that Torres, who went 2-for-4 with a double and a triple Wednesday, also fouled a ball off his left calf and could use a break.

"It got him pretty good," Bochy said, though he added that Torres was available to substitute.

With Torres out, shortstop Edgar Renteria batted leadoff. Renteria began Thursday 6-for-13 with two doubles and two walks since leaving the disabled list June 16. He also was 4-for-7 with two home runs lifetime against Rodriguez.

Catcher Bengie Molina, who might ordinarily rest in day games following night games, started his third consecutive game. Molina was relatively fresh, having left the previous two games for pinch-runners in the sixth and eighth innings. Moreover, Bochy preferred to maintain Molina's partnership with Matt Cain, who started for the Giants.

"They've got a pretty good thing going," Bochy said. "I wanted to leave that battery alone."

Martinez cherishes Red Sox memories

HOUSTON -- Joe Martinez's starting assignment Saturday against the Boston Red Sox won't be his first time to get up close and personal with them.

Martinez's Boston College teams played the Red Sox in annual exhibitions during trips to Florida during spring break. They were somewhat relaxed affairs, as Red Sox stars such as Nomar Garciaparra and Johnny Damon would freely banter with the collegians at the batting cage or even in their dugout.

"It was a lot of fun," said Martinez, who recalled facing Jason Varitek among the current Red Sox.

Though Martinez rooted for the New York Yankees while growing up in South Orange, N.J., he said that facing Boston will be "still a big thrill," since he watched a lot of Red Sox games while attending college.

Martinez prepared for his start by pitching a scoreless seventh inning Wednesday. Before that, the No. 5 starter, whose last turn was skipped due to scheduled off-days, hadn't pitched since working 6 1/3 innings in a June 15 start against Baltimore.

"That definitely helps, to get back into a game atmosphere," Martinez said. "It's tough going so many days and not pitching. You get out of rhythm and there are so many things you have to adjust back to."