A wrist injury had Canada's top-ranked player, sixth-seeded Milos Raonic, badly off his game as he fell 6-4, 6-4 to Adrian Mannarino of France.
But it's looking increasingly likely that Shapovalov will be knocking on the door of the top 100 sooner rather than later, and from there who knows what he could achieve. And no matter the score against Nadal, Shapovalov played aggressive.
Later on Thursday, fifth-seeded Ukrainian Elina Svitolina defeated American Venus Williams 6-2, 6-1, and Spain's Garbine Muguruza beat Australian qualifier Ashleigh Barty 6-0, 3-6, 6-2.
He didn't seem to care, however, as he overcame a first set loss to shock Nadal 3-6, 6-4, 7-6, dropping to the ground and covering his face after the winning shot.
Shapovalov won seven of the final eight points of the third set tiebreaker before closing out the match with a forehand victor down the line. He closed out the match with a forehand victor down the line and celebrated by falling onto his back then covering his face with his hands.
Shapovalov did not bow down, though, earning his first break point of the match in the second game of the second set.
A Polansky double fault gave Federer the break and the Swiss was soon 3-0 up after holding serve to love in the next game.
Federer is 17-0 in his career against the 35-year-old Ferrer, who was ranked third in the world in 2013 but is now at No.33.
The world number three came from a set behind to win 4-6, 6-4, 6-2. "We battled, both tried to find a way to win".
He said that "Denis played well, he has great potential and I wish him all the best".
Monfils, however, fended off four match points to beat Japanese world number nine Nishikori in a three-set thriller 6-7 (4) 7-5 7-6 (6).
The thick thatch of blond hair was flying as Shapovalov launched himself into a forehand that stuck on the baseline for set point. "I think he has ice in his veins and I think he's one of those guys who's going to love the pressure and take on that responsibility".
Federer, though, scraped through to the quarter-finals after outlasting David Ferrer.
Therefore, Federer, who managed 12 aces, has started to serve better and to threaten the service of his rival.
An early break in the decider put Federer in control as a tired Ferrer began to tire and a characteristically deft volley clinched the match.