PSG controlled the ball with more than 70% possession and created a couple of chances on 20 attempts in Wednesday's game, but they were all denied by Metz goalkeeper Alexandre Oukidjia until Angel Di Maria's cross in stoppage time forced Oukidja to parry it to Draxler, who nodded it home for the winner.
The Curitiba-based side top the Group C standings with six points from three matches, ahead of Chile's Colo-Colo on goal difference. Jorge Wilstermann are third with three points.
Veteran striker Roberto Soldado put Granada ahead after just four minutes with a left-foot volley from Yangel Herrera's cross and the Spanish side's nerves were well and truly calmed six minutes later, when Kenedy doubled their lead.
However, under the eccentric tutelage of coach Marcelo Bielsa, Leeds refused to lie down, and equalized in the 12th minute through Jack Harrison after a fine counter-attack.
Stage One involves 32 groups of four players, with the player who tops each group progressing to Stage Two.
The 10th seed, the oldest in the Rome Masters draw at 35, lost 6-0, 7-6 (2) to Musetti who is ranked 249th in the world.
New signing Donny van de Beek came into the game as a substitute and gave United a chance with a goal on his debut, but Zaha's excellent second strike five minutes from time condemned them to defeat.
"Mary is our key player and his goals tell everything," said Shenzhen coach Jordi Cruijff. "His problem is not clear and we have to wait. I hope he will back soon because we have more games in very short period."
Ohaga also ruled that FKF president Nick Mwendwa had no powers to announce the end of the league season, owing to the unavailability of his National Executive Committee (NEC), whose term of office expired in February.
Elsewhere, Russia's Andrey Rublev beat Argentinian qualifier Facundo Bagnis 6-4, 6-4 and will meet Poland's Hubert Hurkacz in the next round.
Russia's Krasilnikov and Stoyanovskiy, who stymied Mol and Sorum in the semifinals of the Rome FIVB Beach Volleyball World Tour Finals and claimed the World Championships in Hamburg in 2019, are thought to be the most powerful competitors for the Norwegians.