MELBOURNE, Australia—Rafael Nadal got to 21 first, breaking the men’s record for most Grand Slam singles titles and doing it the hard way by coming back from two sets down to beat Daniil Medvedev in an almost 5.5-hour Australian Open final that didn’t finish until the early hours of Monday morning. He was broken when serving for the championship at 5–4 in the fifth set but made no mistake the next time. At 5 hours and 24 minutes, it was the second longest Australian Open final after Novak Djokovic beat Nadal in five sets in 5 hours and 53 minutes in 2012. The 35-year-old Spaniard now has one more than Roger Federer and Djokovic, his long-time rivals in the so-called Big Three. With the 2–6, 6–7 (5), 6–4, 6–4, 7–5 win that started Sunday night and was delayed for a while in the second set when a protester jumped onto …