It is hard to see Shapovalov as anything other than a future grand slam champion given his armoury of exciting weapons and competitors' mentality.

But he will have to wait a little longer after 12th seed Carreno Busta, the highest-ranked man left in the bottom half of the draw, battled to a 7-6 (7/2) 7-6 (7/4) 7-6 (7/3) victory.

Shapovalov hit 54 winners, more than double his opponent's tally, but converted only three of 13 break points, and his lack of experience showed in the tie-breaks.

Carreno Busta may not be box office but he is an extremely solid player, a gritty competitor and a very good athlete.

And, while he may never have challenged for a grand slam before, he has been around a lot longer than Shapovalov and taught the youngster the lesson that it is not how many points you win but which ones.

Shapovalov, playing on Arthur Ashe Stadium for the third match in a row, got off to a flying start and served for the opening set at 5-3.

But he could not take that opportunity, nor any of three set points that he created on Carreno Busta's serve at 6-5, and it was the Spaniard who went on to win the tie-break.

The roles were reversed in the second set as Shapovalov broke Carreno Busta when he served for it but again it was the 12th seed who came out on top in the tie-break.

Shapovalov had never played a five-set match in his career so a comeback was an extremely tall task.

He made a fine start to the third set by racing into a 3-0 lead but Carreno Busta pegged him back and again dominated the tie-break to reach the quarter-finals of a grand slam for the second time.

The Spaniard next faces either 16th seed Lucas Pouille or Argentina's Diego Schwartzman.