Kontos suffered a flexor strain and will be placed on the disabled list, Alex Pavlovic of the San Jose Mercury News reports.
Kontos has made eight appearances through the Giants first 14 games, giving up one run on five hits in 5.2 innings while mostly pitching in medium-leverage situations. Flexor strains typically sideline pitchers beyond the minimum 15 days, and the Giants' bullpen is already missing Sergio Romo, who recently suffered the same injury. The team figures to call up a reliever Tuesday.