Jannik Sinner was determined he would not become the third big - name casualty at the US Open in three days . World number one Sinner ' s route to winning a first title at Flushing Meadows - and second grand slam of his career - became a lot easier since he last played after favourites Carlos Alcaraz and Novak Djokovic both crashed out . Sinner was in no mood to join them on an early flight home as he breezed past Australian Christopher O ' Connell in straight sets . " It shows that this sport is unpredictable ," the Italian said . " Whenever you drop a little bit of your level , if it ' s mental , if it ' s tennis - wise or physical , at the end it has a huge impact on the result . " Both opponents who they lost against , they played some incredible tennis . And it happens . " So I just watch on my side what I have to do that I guess I have done also in the last period of time , and then we will see what I can do . That ' s it ." Sinner will be pleased Alcaraz and Djokovic ' s shock exits took the attention away from him and the controversy surrounding his two failed anti - doping tests earlier this year . American Tommy Paul is waiting for Sinner in the next round after the home favourite won a four - set battle with Gabriel Diallo . Britain ' s Jack Draper said his win over Alcaraz ' s slayer Botic van De Zandschulp was not a gimme as he booked his place in the fourth round . The 22 - year - old , who has equalled his best run at a grand slam , won in straight sets on Grandstand court . But Draper said he had work to do , even if it was a predictable case of after the Lord Mayor ' s Show for the Dutchman . " I think it is sometimes difficult when people are saying , ' Oh , like , he should definitely win this match '," he said . " Botic ' s just beaten the number two in the world who ' s won multiple grand slams this year . " He obviously played a really good match and can definitely beat me too ." Draper will next play Tomas Machac , who beat David Goffin . dpa pa dgeSource: The Namibia News Agency