OAKLAND -- The date of Justin Duchscherer's next start is still a mystery, but fortunately the same cannot be said of the right-hander's diagnosis.

Duchscherer visited Nashville-based physician Thomas Byrd on Monday, who found inflammation in the pitcher's strained left hip.

The Oakland starter, who left Thursday's game in Toronto in the fourth inning, will receive a cortisone shot Tuesday and resume throwing in a few days if all goes well. The A's decided to keep him off the disabled list for the time being.

Right-hander Vin Mazzaro, who made 17 starts for the A's last year before a shoulder injury ended his season, will take Duchscherer's rotation slot Tuesday against the visiting Rangers. The 23-year-old is 1-1 with a 2.59 ERA in five games -- four starts -- with Triple-A Sacramento.

The A's have not officially announced the move, and manager Bob Geren didn't mention whom the club will designate to make room for Mazzaro.

Duchscherer, meanwhile, will wait to see how his hip responds to the cortisone shot. Byrd is the same doctor who performed both of the surgeries on his right hip, the first of which came on July 11, 2007, and the second took place Sept. 29, 2008.

Following Tuesday, Duchscherer's next scheduled start would fall on May 11, but two off-days before that give the team flexibility with how to handle the rotation until Duchscherer is given a clean bill of health.