Sargent nearly scored with his first touch for Toronto, latching onto a pinpoint pass in the box from fellow U.S. international Djordje Mihailovic, only to see his shot blocked in front of goal.
He had another golden chance 10 minutes later when a perfectly weighted ball sent him through one-on-one with Ethan Horvath, but the American goalkeeper made the save.
Unfortunately for Sargent and Toronto FC, those missed chances came back to haunt them. A 43rd-minute goal from Dániel Sallói, assisted by Mihailovic, gave the visitors a 1-0 lead, and for much of the match Toronto appeared on course for a second straight victory after opening the season with two defeats.
Then came stoppage time.
On the final kick of the game, a corner fell kindly to Choupo-Moting, whose shot found its way past Reds goalkeeper Luka Garvan.