Then, in the second, with former A's pitcher Fautino De Los Santos on the mound, Weeks reached base again on a free pass and came around to score on Adam Rosales' double. Rosales crossed home plate soon after, when Seth Smith hit one off the right-field scoreboard for a two-run homer, his first of the spring.
Weeks, Rosales and Smith combined to go 6-for-8 with five RBIs from the top three lineup spots.
But the split-squad Padres didn't go down easily. Facing right-hander Dan Straily, San Diego plated two runs in the first, courtesy of RBI hits from former A's Mark Kotsay and Travis Buck.
Straily, fighting for a rotation spot, lasted 1 1/3 innings in his spring debut, giving up two runs on two hits with one walk and one strikeout while utilizing 34 pitches, 23 of them strikes.
"I had to knock the rust off, that's for sure," Straily said. "Having to wait your turn, it feels like it's been a long two weeks, but it felt really good to get out there and throw some pitches."
The Padres added on two in the third inning against righty Bruce Billings and another two in the sixth, when third baseman Cody Ransom launched a two-run homer to left field off southpaw Justin Thomas to make it 8-6.
Oakland's 2012 first-round Draft pick, Addison Russell, walked to open the bottom of the third and stole second base before scoring on infielder Scott Moore's RBI base hit. Andy Parrino also drove in a run.
Up next: Veteran Jason Marquis -- who returned on a one-year, $3 million deal in December -- gets his first start of the spring when the Padres host the Royals at 12:05 p.m. PT on Thursday in Peoria. Marquis won six games last season after signing with the team following his release from the Twins. He'll go two innings. Newcomers Tyson Ross and Wilfredo Boscan are scheduled to go two to three innings. Ross impressed the Padres with his big arm in his spring debut on Saturday, hitting 96 mph with his fastball, though he allowed a two-run homer to Jason Bay and took the loss against Seattle.
Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.