The A's announced on Saturday morning that slugger Matt Chapman will be placed on the injured list with a strained right hip, and will be undergoing surgery on Monday.
The A's release included that the organization expects Chapman to miss the remainder of the season.
Chapman hasn't played since Sept. 6 after dealing with hip tendinitis. The third baseman was hitting .232 with 10 home runs and 25 RBI in 37 games this season.
The A's have given Vimael Machin, Chad Pinder and Tommy La Stella starts during Chapman's absence, and likely will continue with a committee approach down the stretch of the season.
A two-time Platinum Glove winner, Chapman is one of the game's top defenders and brings a powerful bat to the lineup. The A's will have to do what they can to fill that gap as they look to make a postseason run.