"I'm disappointed. I just didn't feel like I could be the player that this team needs me to be in the condition I was trying to play in," Zobrist said. "So I got to get it cleaned up and get back out here as soon as possible."
Oakland purchased the contract of infielder Max Muncy from Triple-A Nashville to take Zobrist's place on the 25-man roster. Muncy started at third base and batted seventh for Saturday's game against Houston for his major league debut.
Zobrist was batting .240 with one homer and eight RBIs in 14 games. He has started games at second base, left field and right field this season.
Zobrist hurt his knee sliding into second base on Sunday in Kansas City. He sat out three games before being used as a pinch-hitter Thursday in Anaheim. He was the designated hitter Friday night to see if he could play through the pain but decided after the game surgery was his best option.
"I just wasn't getting out of the box well at all, and frankly, the worst thing out of it was just trying to swing," he said. "When I swung right-handed specifically it put a lot of pressure on that front knee, the left knee. I just didn't feel like I was in the kind of condition I need to be to help the club."
Zobrist said he will need to undergo arthroscopic surgery to trim the meniscus that is causing so much pain. Players usually miss four to six weeks with such an injury.
"We brought him in here for a reason," manager Bob Melvin said. "He's a significant factor for us. Depending on the timetable we'll get him back for most of the season. These are things that you have to deal with over the course of a season."
Muncy was batting .293 with one homer and 10 RBIs in 15 games with Nashville. He is tied for the Pacific Coast League with 12 walks and has a .408 on-base percentage.
Muncy got a phone call in the middle of the night in the Nashville to come to the majors. He quickly repacked his suitcase that had been ready for a road trip to New Orleans and caught a 6 a.m. flight. He arrived at the stadium a couple of hours before the game on one hour of sleep
"It's a dream come true," he said. "It will be a fun day. Regardless of the outcome for me it will be a fun day."
Muncy, normally a first baseman, got work at third base in spring training and will get most of his time there for the A's. He started Saturday to give banged-up Brett Lawrie a day off.
The A's designated left-hander Eury De La Rosa for assignment to clear a spot on the 40-man roster for Muncy.