Cespedes helped Oakland crash San Francisco's party when he sent an 82 mph changeup well over the wall in left to put the A's ahead 2-1 in the fourth. Cespedes dropped his bat and stared for a moment before trotting around the bases, leaving Lincecum looking lost again.
"Not the guy that you worry about the most," A's manager Bob Melvin said of Cespedes.
Cespedes also hit a towering homer off Lincecum in his previous start. Lincecum gave up five runs and six hits in three innings of a 12-5 loss to the A's last week in Arizona.
"He just made two bad pitches look like home runs," Lincecum said. "Good thing he's in the AL."
Lincecum labored for his final five outs. Sogard hit an RBI single off Lincecum in the fifth. After a two-out walk to Jed Lowrie, Lincecum was pulled for lefty Jeremy Affeldt, who gave up a three-run shot to Josh Reddick that put Oakland ahead 6-2.
San Francisco's lanky right-hander has said all spring that he is determined to redeem himself and prove his worth as a starter in a contract year. He worked out with a personal trainer during the offseason to add about 10 pounds of strength, tweaked his mechanics and even cut his long locks for a fresh start.
Instead, a lot of the same troubling signs have surfaced this spring, with Lincecum coming unraveled in one bad inning the way he so often did last year. He finished 0-3 with a .324 opponents' batting average in exhibition games.
Lincecum is slated to slide into the third spot in the rotation behind right-hander Matt Cain and lefty Madison Bumgarner.
"You want to take something from (spring), but you don't want to take everything just because we were down in Arizona most of time, and it's a different game," Lincecum said. "Guys are trying different things. But you still have to compete. You still want to show better numbers."
NOTES: Giants 3B Pablo Sandoval took batting practice and fielding drills before the game. Bochy said the World Series MVP could play Friday or Saturday and possibly be ready for opening day. Sandoval has been sidelined since March 16 because of an inflamed nerve in his right elbow. ... Oakland INF Hiro Nakajima is unlikely to play during the series after straining his left hamstring Tuesday, Melvin said.