Duda was pulled from Friday's game in the seventh inning after he aggravated his back injury. He has started just three of the Mets' last nine games since Aug. 11.
“It just kind of jammed up again,” Duda said after Friday's game (Aug. 22). “We'll take a look at it tomorrow and see how it goes.”
Duda told reporters on Saturday he will see Dr. Robert Watkins, the same doctor who treated David Wright's stenosis, in California for a second opinion (Aug. 22).
Michael Cuddyer and Daniel Murphy have taken over at first base in Duda's absence.
Duda is hitting .247 with 21 home runs and 56 RBIs this season.
Alvarez, 26, has a 2.75 ERA in 39 1/3 innings for Las Vegas and Double-A Binghamton this season. He appeared in four games in the majors last year.