The world number one powered through a rapid-fire opening set and overcame a wobble as he started the second set by dropping serve.
The defending champion prevailed in a brief 71 minutes as he claimed an eighth victory in a row at this event and his 30th this season.
“I felt great on the court today, you could see that,” said the Italian, who turns 24 on Saturday. “But every day can be different. Let’s see what I can do in the semis.”
Auger-Aliassime meekly lost the opening set after less than 30 minutes, delivering three double-faults in the final game.
After dropping his serve early in the second Sinner broke back to level at 2-all, eventually advancing as Auger-Aliassime coughed up his eighth double fault on match point.
“I served well today, that was the key for me,” Sinner said. “I had a small drop in the second set and I’m happy that I broke back. He moves and serves well, he’s difficult to play.”
In women’s action, French Open champion Coco Gauff beat Lucia Bronzetti 6-2, 6-4 to reach the quarter-finals.
The second-seeded American’s game showed minor rust after a bye in the previous round.
“I could have maybe made some more first serves in that second set, but overall, I had a lot of aces and unreturnables,” said Gauff, the 2023 Cincinnati champion who went on to win the US Open title that year.
Gauff, who was broken once in each set herself, finally secured a spot in the last eight with a concluding break of the 61st-ranked Italian’s serve as Bronzetti hit long after 79 minutes on court.
The American next takes on seventh seed Jasmine Paolini, who crushed 2024 Wimbledon champion Barbora Krejcikova 6-1, 6-2.
Krejcikova had treatment on her left foot in the second set and her movement was clearly hampered.
Paolini, the 2024 Roland Garros and Wimbledon finalist, won seven straight games on the way to a 4-0 second-set lead and rallied from 0-30 down in the final game to advance.
“She’s a great player and can do anything she wants with the ball,” Paolini said. “But I don’t think she was at 100 percent today. I’m glad I stayed in the match mentally to the last point.” (AFP)