The Canadian, however, saved two match points on Thursday and made up for a one-set deficit to defeat the Italian Jannik Sinner 2-6, 7-6 (7/1) and 6-1.
Trailing 4-2 in the second set, Auger-Aliassime broke Sinner and brought the game back on even serve.
While serving and able to force a tiebreaker, the Quebecer overcame a 15-40 deficit to win the game. He easily won the tiebreaker and then had the wind in the sails for the deciding leg.
The seventh seed in Ohio triumphed after 2 hours 26 minutes of play. Auger-Aliassime led 14-4 in terms of aces.
It was the second duel between the two players. The Canadian won the prize on each occasion.
For the second year in a row, Auger-Aliassime reached the quarter-finals of the US Open tune-up tournament.
In the quarter-finals, the 9th racket in the world will cross swords with the Croatian Borna Coric, 125th.
Shapovalov held back by Medvedev
Canadian Denis Shapovalov’s career ended in the round of 16. The Ontarian and 21st in the world fought a good battle against No. 1 Daniil Medvedev, winner in two identical sets of 7-5 after 1 h 47 min.
The Russian, winner in Ohio in 2019, needed to break twice to pocket the first set. It’s at 11e game that he forced his opponent to foul.
Shapovalov had however managed to regain service to equalize at 4-4, thanks in particular to a superb rally from the baseline.
The second set was even tighter, Medvedev missing four break points at 4-4. Party postponed, the Russian, as in the previous round, made the difference on the next engagement of his rival, still too much at fault (29 direct), to open the way to a third victory in five confrontations against the Canadian.
Medvedev is assured, thanks to the elimination in the second round of Rafael Nadal the day before, to remain in first place in the standings before the United States Open, where he will defend his title.
In the quarter-finals, he will face the American Taylor Fritz, seeded 11th.
Earlier in the day, Fritz overthrew the Russian Andrey Rublev (no 6), finalist of the event last year, 6-7 (4/7), 6-2 and 7-5.
It was at the end of a third round of an excellent level that Fritz ended up having the last word on the Russian, whom he had notably beaten in March, in the semi-finals of the Indian Wells Masters, before win the title against Nadal.
The 24-year-old American, who now leads four victories to two in their confrontations, relied in particular on his formidable backhand, as effective in attacking along the line as in defending, like this superb cross lob which put him in position to break at 5-5 in the final set.
Other round of 16 results:
- Stefanos Tsitsipas (GRE/no 4) beats Diego Schwartzman (ARG/no 13) 6-3, 6-3
- John Isner (USA) defeats Sebastian Korda (USA) 7-6 (7/3), 1-6, 7-6 (7/4)
- Cameron Norrie (GBR/no 9) beat Ben Shelton (USA) 6-0, 6-2
- Carlos Alcaraz (ESP/no 3) beats Marin Cilic (CRO/no 14) 7-6 (7/4), 6-1
- Borna Coric (CRO) defeated Roberto Bautista (ESP/no 15) 6-2, 6-3