Germany took control of UEFA European Under-21 Championship qualifying Group 6 after coming out on top as the section's two perfect starters met in Wiesbaden.
Both teams had won their two opening fixtures and it was the home side who seized the initiative with Philipp Hofmann's 25th-minute goal. Kevin Volland added a second in added time to secure the points for Horst Hrubesch's men, who are yet to concede in qualifying.
While Germany dominated possession from the off, Montenegro regularly reminded them of the danger they posed on the counter. For the hosts it was the lively Amin Younes dictating the pace in midfield, though the opener came from a Johannes Geis corner which was headed in powerfully by Hofmann.
Marc-André ter Stegen needed to be at his best to maintain his team's advantage, denying Stefan Mugoša and Luka Djordjević in one-on-one situations. Hofmann struck the bar after the break as Germany sought to put the game to bed, which Volland eventually did in the 92nd minute, crashing in after fine work from André Hoffmann.