Scherzer exited his start Saturday against the San Francisco Giants after 12 pitches. The seven-time All-Star told reporters after the game that he tweaked his groin, and an MRI revealed it was inflammation with no strain.
The team is taking a cautious approach in placing him on the IL.
Injuries and depth have played significant roles as Washington has posted a 28-35 record. Stephen Strasburg has only thrown 21.2 innings with a right shoulder injury. Erick Fedde, who has a 3.86 ERA in nine starts, also spent time on the injured list.
The 36-year-old Scherzer continues to be the ace of the Nationals pitching staff. The right-hander ranks ninth in MLB with a 2.21 ERA, fourth with a 0.81 WHIP and sixth with 104 strikeouts.
Washington's rotation without Scherzer is not strong. He's the only pitcher with an ERA under 4.00 in at least 10 starts.