The best chances were continuing to fall the way of Cavani, who just could not find a way through in a frustrating first half for the Parisians, with his final attempt before the interval striking the post.
Metz had a couple of opportunities of their own in the French capital, meanwhile, one of which Kevin Trapp did well to keep out in a big warning to PSG.
It was Lucas who finally opened the scoring for his side, taking the ball in his stride just inside the box and sweeping home past the reach of Thomas Didillon in the Metz goal.
Renaud Cohade gave the hosts another major let-off when failing to get the better of Trapp on the hour mark, and that proved to be a key moment in the match as Kurzawa glanced home unmarked from a corner for his second goal in as many games.
A late goal from Verratti at the death ensured that it would be a winning start for Emery on home soil and a second win in succession for the French giants.