Duda had an MRI and was examined by a doctor Saturday. He was told to take a few days to rest and has further tests scheduled to determine if a disabled-list stint is warranted. He had received an anti-inflammatory injection earlier in the week.
"It's too early to tell," said Mets manager Terry Collins, regarding how long Duda would be out.
Duda has a .231/.297/.431 slash line with seven home runs this season, but was hitting .171 with only two extra-base hits and no home runs in his past 13 games. He hit 30 and 27 home runs the past two seasons.
"Having him out of the lineup is a huge loss for us, especially against right-handed pitching, which we're going to see two games here and two games in D.C. (next week)," Collins said. "We have to look at the big picture. We can't aggravate this thing to where it becomes a major issue. We hope that it won't."
Wilmer Flores, who was expected to be Duda's backup at first base this season, is expected to start a rehab stint on Tuesday, though Collins didn't specify where that would be. Flores can be activated on Friday, in time for the Mets' series against the Dodgers. Eric Campbell, who started for David Wright at third base on Friday, replaced Duda in the lineup on Saturday.
Harvey throws from Citi Field mound: The Mets did not reveal the date for Matt Harvey's next start, which will be either Monday or Tuesday, but Harvey did throw to hitters from the Citi Field mound for about 25 minutes on Saturday. Neither Harvey nor Collins spoke to reporters after the session. The Mets closed off the dugout to reporters during the session.
If Harvey starts on Monday, he would be pitching on three days rest for the first time in his career.