Recent 8th finalist at the Australian Open, the 33-year-old Frenchman suffered a little against a player who had never done better than 172nd place in the ATP rankings in 2019 and who, at 30, has never participated in a Grand Slam main draw.
But the current 381st in the world had taken a set from Andrey Rublev during the last final phase.
And the magic of the Davis Cup almost operated once again.
Broken from the start, the Val d'Oisien immediately picked up.
During a first round of good quality and very balanced, the French leader snatched the opposing service in the tenth game to win the first act 6-4.
Without complex the Ecuadorian left-hander continued to upset the tricolor left-hander in the second act.
To discover
Davis Cup: Schedule and results
Mannarino thus erased three break points in the fifth game. But he yielded in the ninth game of the second act and did not convert two break points in the tenth game won by the Ecuadorian (6-4).
The 58th in the world did not panic and the outsider Quiroz foiled, accumulating unforced errors in the last act.
Mannarino took the opportunity to fly away with a double break and play five consecutive games.
France leads logically 2-0 after the first two singles.
It's up to the Mahut-Herbert pair to finish the job this Saturday.