CINCINNATI -- Oakland Athletics outfielder Miguel Andujar will have season-ending surgery, manager Mark Kotsay said Wednesday.

"We are going to miss him," Kotsay said. "He was a big contributor and a big part of this club's success over the past few months. Hopefully the surgery will go well. We'll definitely look forward to having him back next year."

Andujar was placed on the 10-day injured list Wednesday, retroactive to Sunday, with what was described as a core muscle injury, and infielder Nick Allen was recalled from Triple-A Las Vegas.

"Miguel's been playing with this issue for a few weeks," Kotsay said. "It's a credit to Miguel and testament to the character of the young man to continue to play. It just got to a point where it was uncomfortable sleeping and impacting his daily life as well."

Andujar, the team's primary left fielder for most of the season, has not played since Saturday. Daz Cameron will get the bulk of the starts in left field, but Kotsay said Allen, Tyler Nevin, and Seth Brown also could see time there.

"We like to match up," Kotsay said. "We'll take a look at the roster"

This is Andujar's second stint on the IL after beginning the season there following right knee surgery. In 75 games since being reinstated, Andujar batted .285 with four home runs and 30 RBIs. He ranks third among major league outfielders with 10 assists.

The 25-year-old Allen batted .171 with one home run and three RBIs in 28 games before being optioned to Triple-A on May 3. He batted .345 with 26 doubles, a triple, seven homers and 51 RBI in 81 games for Las Vegas.