The 33-year-old striker, who came on after the interval, latched onto a through pass from teammate Wu Xi before sending it into the net in the 65th minute.
But things didn't go as organisers may have expected.
Germany started brightly on home soil and created the first chance of the game as Toni Kroos' cross into the box allowed Thilo Kehrer to test Spain goalkeeper David de Gea in the 11th minute.
Flamengo netted twice in quick succession after the restart: first with a stunning first-time effort from playmaker Everton Ribeiro and then with a cool Arrascaeta finish after a counterattack.
Arrascaeta restored his team's two-goal advantage with a diving header in heavy rain but Jose Pimentel responded with his side's second goal just before halftime.
"My full efforts are totally focused on leading the Badminton World Federation and fulfilling my role as IOC member. I would like to thank the badminton and sporting community for their ongoing support and I look forward to leading the BWF as we plan for our safe return to international badminton," he said.
Jumbo Team's Van Aert produced a powerful sprint in the slight uphill finish to win by half a wheel ahead of Cees Bol and Sam Bennett.
Moreno remained in the thick of things and kept Germany's defense busy as the striker hit an effort on target from a promising position in the dying seconds of the first half.
"I rode my tempo and gave it all to create a gap big enough to win."
Iran's match with Uzbekistan, previously set for September 7, has been rescheduled for October 8 in Tashkent's Bunyodkor Stadium.
Djokovic will face Jan-Lennard Struff for a spot in the round of 16. The German needed one hour and 40 minutes to move past American Michael Mmoh 6-2, 6-2, 7-5.