CLEVELAND — Indians starter Jake Westbrook is expected to miss at least one month with a muscle strain in his lower back, an injury the team initially figured would keep him out only for a few starts.

Westbrook hurt himself while throwing a pitch to Minnesota's Mike Lamb last Saturday. He was placed on the 15-day disabled list Tuesday. The right-hander is 1-2 with a 2.73 ERA in four starts.

Westbrook received a cortisone shot in his back Friday.

Indians trainer Lonnie Soloff said the timetable for Westbrook's recovery changed because the symptoms of his injury persisted for a week since he got hurt. Soloff said the injection seemed to help Westbrook.

Soloff also said closer Joe Borowski will begin playing catch on Monday. Borowski has been out since April 15 with a strained triceps muscle and is expected to miss one month.