Syndergaard (lat) threw a simulated game Monday, Matt Ehalt of The Record reports.
Prior to Monday, manager Terry Collins said Syndergaard needed to face live hitters again before returning to action, so if he checks out following Monday's simulated outing, his next appearance could be for the big club. Thor could return to the mound over the weekend against the Nationals, though he would likely be on a pitch count if he does so.