Sinner was pushed hard by the 19-year-old Brazilian, trailing 3-6 in the first-set tiebreak before rallying to close out the match 7-6 (8-6) 7-6 (7-4) in the Southern California desert on Tuesday (Wednesday AEDT).
“I am very happy winning this match,” the Italian said.
“Joao is an incredible talent. He was serving really well. I was trying to be as aggressive as possible and that was the key to get through against the incredible talent.”
Four-time major winner Sinner next meets the home favourite Learner Tien on Friday (AEDT) for a place in the last four.
“I feel he (Tien) is a very consistent player, and I am very happy to face him again. He has improved a lot since the last time we met,” Sinner said of his upcoming American opponent.
AAP