Andy Murray admits adding to his three grand slam titles will be a tough ask but insists he will continue to "shoot for the stars" for the rest of his career.
The 33-year-old Scot's US Open comeback was ended in the second round by Canadian youngster Felix Auger-Aliassime, 6-2 6-3 6-4, but 20 months after he announced he may have to quit tennis due to a chronic hip injury, just being on the starting grid at Flushing Meadows was a triumph in itself.
Murray's metal hip was certainly put to the test in an epic four-and-a-half hour, five-set marathon against Yoshihito Nishioka in the first round.
Those exertions proved just too much against rising star Auger-Aliassime, with the 20-year-old playing arguably the finest match of his career.
Nevertheless, Murray said: "Even after that I would say I'm more positive about what I could do in grand slams than I was before I came over here.
"To come over here and play a couple of tough matches in Cincinnati, and I played certainly one very tough match here, and my right hip felt good. That's really, really positive.
"There are other things that need to get better, but I would say I'm more positive now than I was a couple of months ago.
"In terms of winning grand slams again, that's going to be extremely difficult to do. It was hard enough when I had two normal hips. So it will be difficult, but I'll keep trying. Why not? Why shouldn't I try my hardest to do that? And if I don't, that's all right, but I might as well shoot for the stars."
Cameron Norrie's run ended with a third-round loss to Spain's Alejandro Davidovich Fokina.
Victories over ninth seed Diego Schwartzman and Federico Coria made it Norrie's best grand slam showing and he looked to have a very good chance of reaching the last 16 against a 21-year-old opponent ranked just inside the top 100. But he went down 7-6 (2) 4-6 6-2 6-1.
British interest in the singles ended with a disappointing defeat for Dan Evans in his delayed second-round match against Frenchman Corentin Moutet, losing 4-6 6-3 7-6 (5) 7-6 (1).