ATP Finals 2018: 5 Talking points from Alexander Zverev's stunning win over Novak Djokovic

#4 Zverev's supersonic serving and returning

Nitto ATP Finals - Day Eight: Djokovic lost his serve 3 times

Zverev out-served Djokovic by hammering down 10 aces and losing his serve just once. Surprisingly though, he also out-returned Djokovic by breaking him as many as four times!

Djokovic hadn’t lost a single set all the way up to the final. But a stray netted forehand turned into a series of unforced errors and gave Zverev the advantage. After being broken for the first time in the tournament, Djokovic looked shaken. That was when his game started sliding downhill

Zverev’s true test was in keeping his nerves and serves steady to wrap up the first set. He closed with three aces and a couple of short rallies, showing everyone that he wasn't about to break down in the face of pressure.