Montero is expected to start in place of the injured Noah Syndergaard (back) on Friday against the Marlins, Anthony DiComo of MLB.com reports.
Montero was the backup plan for Thor if the ace was initially unable to make his previously scheduled start Sunday, so this shouldn't come as too much of a surprise. The 26-year-old struggled as a reliever with the big club to start the season, posting a 9.45 ERA and 3.60 WHIP before being optioned back to Triple-A, where he settled in as a starter. In two starts (10.1 innings) with Las Vegas, Montero allowed just two runs on four hits with an impressive 16:3 K:BB. It's unclear whether Montero will replace Syndergaard for more than one game, but that probably hinges on Friday's performance.