Maxwell, who played previously for three teams, had seen the Giants record similar victories, particularly when he played for Houston in 2012-13.
"They always found a way to win when I was playing with the Astros," Maxwell said. "Guys expect to win."
Maxwell expected to deliver as he faced Padres right-hander Nick Vincent in the 12th. With one out, Brandon Crawford helped set the stage for Maxwell by lifting a popup to shallow left field that shortstop Clint Barmes reached for but missed; the ball fell for a two-base error. After Casey McGehee flied out, Vincent intentionally walked Gregor Blanco to force the Giants' hand with reliever George Kontos due up next. Up came Maxwell, who received a start in Wednesday night's series finale at Arizona and went 1-for-5.
Said Maxwell, who struck out in his only career at-bat against Vincent, "He was making some tough pitches. But I faced him a few years ago so I kind of knew what he featured."
Maxwell drove a 3-2 slider to right-center field, scoring Crawford.
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.