Peterson will start Sunday's game against the Phillies in Philadelphia, Laura Albanese of Newsday reports.
Peterson has surrendered nine earned runs in just 6.2 innings across his last two appearances out of the bullpen, but the Mets will nonetheless turn to him to fill the open spot in their rotation in the series finale. The Phillies have turned in a weak .670 OPS across their last 10 contests, but the 30-year-old southpaw's recent performance puts a low ceiling on his fantasy appeal.