The A's will call on pitching prospect Daniel Mengden to start Saturday's game in Cincinnati, according to a baseball source. The right-hander will be making his Major League debut.
The club has not commented on or confirmed the move.
Mengden, who is ranked No. 14 among Oakland prospects, has absolutely dominated at the Minor League level this season, posting a combined 1.19 ERA in 11 starts between Double-A Midland and Triple-A Nashville with 67 strikeouts in 68 1/3 innings.
In seven starts for Nashville, Mengden has limited opponents to seven earned runs in 45 1/3 innings.
The 23-year-old, originally a fourth-round Draft pick by the Astros in 2014, was acquired by the A's last summer in the Scott Kazmir deal.