This one was probably the most hair-raising hat-trick I've seen live (others might have been better but not as special). Similar circumstances as Rooney vs. Fenerbahçe in terms of a prodigious talent having a landmark game, but an even bigger occasion as it was a Clásico vs. the eventual champions. Every time you thought Madrid were going to seal the deal, the kid magically pulled one back (equalized the first goal, then the second goal and finally Ramos' presumptive winner in the 90th minute) — and was the biggest difference-maker on a pitch that also contained the likes of van Nistelrooy (Pichichi winner in 2006/07), Henry (reigning Ballon D'Or bronze medalist), Ronaldinho, Raúl, Xavi...
At least for our generation it's comparable to Pelé vs. France in 1958.
Honorary mentions: Shevchenko vs. Barcelona in 1997, Lucas vs. Ajax in 2019, Bergkamp vs. Leicester in 1997, Cristiano vs. Wolfsburg in 2016, Rossi vs. Brazil in 1982 for non-live.