CHICAGO - Although he made no official announcement, Barry Zito believed his playing career had concluded with the end of the minor league season earlier this month.

That's why he didn't initially know how to react when Oakland Athletics general manager Billy Beane called Monday and asked if he was up for pitching in the major leagues again.

"I turned the page on the game eight days before, so it was a little daunting and strange to have to pull that page back again after 15 years," Zito said Wednesday after joining the A's before the game with the Chicago White Sox.

"Just, was it the best thing for me? It ended up that my wife was really telling me all the things I needed to hear and ended up saying this is going to be a lot of fun," he said.

Zito returned to the A's on a minor league contract this season and spent the entire year with Triple-A Nashville, where he went 8-7 with a 3.46 ERA in 24 games. He last pitched for the A's in Game 1 of the 2006 AL championship series against Detroit and has not pitched in the majors since 2013, with San Francisco.

Now, Bay Area baseball fans are hoping for a Zito vs. Tim Hudson matchup next weekend at the Coliseum. They were part of Oakland's Big Three along with Mark Mulder. Hudson is retiring after this season and Zito might follow.

"I'm really happy for him," Hudson said. "I'm sure he appreciates it and I think he deserves it. I'm sure the fans in Oakland will ultimately appreciate it as well."

Zito won the 2002 AL Cy Young Award with Oakland and went 102-63 with a 3.53 ERA over seven seasons with the A's before leaving as a free agent to sign a $126 million, seven-year deal with the Giants in December 2006.

The left-hander with that nasty curveball delivered two crucial wins during San Francisco's 2012 World Series run for their second of three championships they've won the past five seasons. He earned a victory in Game 5 of the NL championship series against the Cardinals at Busch Stadium facing elimination, then in the opener at home of a World Series sweep against the Detroit Tigers.

He took the 2014 season off before rejoining the A's for one more pitching run.

"It's a great story. It's about playing the game because you love it, because you have a passion for it," Giants manager Bruce Bochy said Wednesday.

The 37-year-old Zito will pitch out of the bullpen.

"It's gonna be great to bring him home and get him in games in our place in front of our crowd," Oakland manager Bob Melvin said. "They love him there. Particularly when we play the Giants, it's gonna be a really exciting weekend. It's really gonna add to that having him there."

Zito said he hasn't thought about playing beyond the three weeks remaining in the season, but conceded it would be fitting if he ended his career in an A's uniform.

"Absolutely," he said. "This is where I started. That mound in Oakland is where I threw my first major league pitch and I don't know how it's all going to shake out with the rotation, days and all that, but I'm going to throw one of my last major league pitches probably on that mound. That's like storybook, it's amazing."

To make room on the 40-man roster, the A's placed right-hander Jesse Chavez on the 60-day disabled list with a broken rib.