Gio Gonzalez (shoulder) placed on DL

— -- The Washington Nationals have placed struggling left-hander Gio Gonzalez on the 15-day disabled list with inflammation in his pitching shoulder.

The Nationals announced the move Sunday morning, less than 24 hours after Gonzalez was roughed up in a loss to the New York Mets, allowing five runs in a season-low three innings.

It was the second straight poor outing for Gonzalez, who yielded seven runs and nine hits in just 4 1/3 innings last Sunday against the Oakland Athletics, his former team.

The 28-year-old danced around questions about his health Saturday.

Gonzalez saw his ERA rise to 4.62 with Saturday's loss to New York and had been slated to undergo an MRI on Sunday. It marks the first time in his seven-year career that Gonzalez had been placed on the DL.

The Nationals recalled right-handed reliever Ryan Mattheus to replace Gonzalez on the 25-man roster.

The injury to Gonzalez is the latest this season to strike the Nationals, who already are without star outfielder Bryce Harper, slugging third baseman  Ryan Zimmerman and veteran first baseman Adam LaRoche.

Gonzalez is 3-4 in nine starts this season, his third with Washington. A two-time All-Star and 21-game winner in 2012, Gonzalez is 73-52 with a 3.64 ERA in 168 career games with the Nationals and A's.

Mattheus has 140 career appearances with the Nationals, including two this season. He has not allowed a run in three innings.

The Associated Press contributed to this report.