Casper Ruud has No 1 slot in sight after US Open rout of Matteo Berrettini

• Ruud beats Berrettini 6-1, 6-4, 7-6 (4) to reach semi-finals
• Norwegian's progress signals further changing of the guard

As Frances Tiafoe basked in the glory of his quarter-final upset of Rafael Nadal on Monday night, he was reminded that at some point soon the big three would retire, with more opportunities to come.

He responded with a cynical smile, not missing a beat: Been saying that for how many years now?" But what is clear is that a new men's grand slam champion will be crowned at the US Open, and this tournament will provide another glimpse into the future of men's tennis.