Whilst YE#1 is the greater accomplishment more generally, for Nadal I think the YEC gap on his resume makes it a more significant goal. Can easily seize both, but if I were him I'd be extremely motivated to finally tick that off.
Interesting stat about the U23s in Masters semis. Had to go searching, and came up with Hamburg (clay) in May 1999. 23yo Rios beat 21yo Zabaleta, with 22yo Lapentti & Moya in the SFs. Of course, by that point Rios had already been #1, Moya had a slam, Lapentti had the AO SF. Even among the quarterfinalists, Henman was oldest at 24yo.
Surprised that the nextgen couldn't achieve this between 2000-04. With guys like Hewitt, Safin, Ferrero, Roddick, Nalbandian, Federer, among others, you'd think there would be an U23 Masters SFs in there somewhere. Paris 2000 is close, as Guga & Scud had only just turned 24yo. Rome 2001 & Hamburg 2002 had no 25yos, that's the next best I've found.
Clinical from Medvedev, predictable from Zverev. That was anyone's first set up until he gifted those 2 points to Medvedev on his own serve to lose the set. Never really recovered after that while Medvedev just did what Medvedev does, so reliable from the back of the court and his court coverage for someone 198cm tall is remarkable.