Already facing an uphill climb to reach the postseason, the defending World Series champion Boston Red Sox will be without their ace for at least the next week. It sounds like there's a chance he will be out much longer too.

The Red Sox announced Saturday afternoon that left-hander Chris Sale has been placed on the 10-day injured list with elbow inflammation. The move is retroactive to August 14. The team did not announce the severity of the injury or give a firm timetable for Sale's return.

President of baseball operations Dave Dombrowski told reporters, including MLB.com's Ian Browne, that an MRI showed the inflammation in Sale's elbow following his most recent start. Dombrowski added this is not something Sale has dealt with all season.

Sale, 30, missed most of the second half last year with shoulder trouble. Despite that, the Red Sox signed him to a five-year extension worth $145 million back in spring training. The deal covers 2020-24. Sale has a 4.40 ERA in 147 1/3 innings this season, making this his worst season since transitioning to the rotation back in 2012.

The Red Sox demoted trade deadline pickup Andrew Cashner to the bullpen after he allowed 29 runs in 30 1/3 innings in six starts following the trade. He'll likely slide back into the rotation to replace Sale. There have been rumblings that Nathan Eovaldi will return to the rotation, though he remains in the bullpen for the time being.

Boston comes into Saturday with a 65-59 record and a 6 1/2-game deficit for the second wild-card spot. SportsLine puts their postseason odds at 2.1 percent.

Righty reliever Ryan Brasier was called up to replace Sale on the roster, the Red Sox announced.