But an MRI taken Tuesday showed a condition in the left AC joint that is very similar to the problem in the right shoulder that required bone-shaving arthroscopic surgery in 2003.
"I've got some soul-searching to do," the 34-year-old Klesko said of the decision on whether to have the surgery. "I want to talk to family, friends, doctors, everyone.
"I don't want to miss two to four months. At the same time, I don't want to be on that roller coaster of being able to play two days and then having to miss four games ... of playing at 60 to 70 percent."
Klesko joined the Padres in 2000 via a trade from Atlanta and is in the final year of a contract that pays him $10 million this season. The Padres have shown no interest in retaining Klesko.
Meantime, Adrian Gonzalez, the San Diego native who was the first overall pick in the 2000 draft, had three hits including a homer Wednesday and is off to a 5-for-8 start to the season. Gonzalez, 23, is already considered a far superior defensive first baseman than Klesko.
REPLAY: Left-hander Shawn Estes gave up only five hits in his first start for the Padres on Wednesday night, and four of those didn't make it out of the infield. But the Giants parlayed three of the hits and three walks into three runs in the sixth to defeat San Diego 3-1.
One of the hits came on a bases-loaded chopper by Moises Alou to the third base side of the mound. Estes made the play, but he couldn't get a grip on the ball to throw home, allowing the game's first run to score.
The loss marked the eighth straight season that the Padres failed to get off to a 2-0 start.