SAN FRANCISCO -- Though Todd Wellemeyer is officially listed as the Giants' starting pitcher for Friday night's series opener against the Houston Astros at AT&T Park, it's possible that Tim Lincecum could be moved up a day and would start that game instead.

Without mentioning names, manager Bruce Bochy didn't rule out a possible juggling of the rotation.

"We're talking about some things," Bochy said Tuesday when asked if the Giants would stick with their current alignment. He added that he'd probably finalize his pitching plans later Tuesday or Wednesday.

Lincecum would pitch on his usual four days' rest if he started Friday and would receive an extra day's break if he worked Saturday -- which might be preferable, since he threw 116 pitches in six innings last Sunday at New York.

Lincecum's the only Giant among the top four starters who's subject to being moved up, since he pitched immediately before Monday's scheduled off-day. If Lincecum were to start Friday, Wellemeyer would pitch Saturday so Barry Zito, Matt Cain and Jonathan Sanchez could get their regular rest.

F. Sanchez shines in first rehab game

SAN FRANCISCO -- Giants second baseman Freddy Sanchez opened his injury rehabilitation assignment with high-Class A San Jose in rousing fashion Tuesday night, doubling twice in four at-bats and driving in three runs at Visalia.

Sanchez, recovering from left shoulder surgery, grounded out and flied out in his first two plate appearances before rapping his hits. His first double drove in one run before his next sent home a pair.

Sanchez sustained injuries to his shoulder and left knee toward the end of last season, but his knee hasn't been an issue this year.

"It is encouraging," manager Bruce Bochy said. "It looks like he's on his way. Hopefully we'll have him up here pretty soon."

Burriss visits Giants to continue rehab

SAN FRANCISCO -- Infielder Emmanuel Burriss, who has recovered enough from left foot surgery to perform baseball-related activities, arrived Tuesday to spend the homestand working out with the club.

"We'll get a measuring stick of where he is [in his recovery]," manager Bruce Bochy said, adding, "A little change of scenery keeps you motivated."

Burriss said that he hopes to begin playing in the Minors on an injury rehabilitation assignment in four weeks. At best, he said, he might be able to rejoin the Giants before the All-Star break if the club needed him.

"This team's rolling," he said. "I just want to be a part of it."

Burriss, 25, has been rehabilitating at the Giants' training complex in Scottsdale, Ariz., since undergoing his procedure in late March. He said that he began taking ground balls last week and has no pain in the foot, which he broke for the second time in eight months in early March.

Bowker making mark in a pinch

SAN FRANCISCO -- Pinch-hitting is probably not the niche John Bowker wanted to find with the Giants as the season started. But his success off the bench has made a definite impression with manager Bruce Bochy.

"I like the at-bats he has been giving us," Bochy said of Bowker. "He looks more comfortable in the role."

Bochy acknowledged that pinch-hitting, which is difficult under any circumstance, usually is particularly challenging for younger players such as Bowker for an obvious reason: They lack experience. Most accomplished pinch-hitters were regulars at some juncture in their careers. In fact, Bochy said that Bowker eventually "is going to get some starts."

Bowker, the Giants' Opening Day right fielder who lost his job to Nate Schierholtz, maintains a simple approach when he pinch-hits.

"I try to hit the fastball," said Bowker, who entered Tuesday batting .375 (3-for-8) off the bench. "You've got one at-bat; you don't want to miss that good pitch."

Bowker had a particularly productive series last weekend at New York, where he homered off Mets closer Francisco Rodriguez to tie the score in Friday's ninth inning, drew a walk Saturday and coaxed another walk Sunday in front of Aaron Rowand's go-ahead home run in the eighth inning.