Before each day's play at the 2020 Australian Open, we'll preview three must-see matches.
 Daniil Medvedev vs.  Stan Wawrinka
Medvedev and Wawrinka have played twice, and Medvedev has won both times in four sets. There were, possibly, extenuating circumstances in both cases. Their first match, at Wimbledon in 2017, was also the last that Wawrinka played before undergoing knee surgery that year. And during their second match, at last year’s US Open, Stan looked less than fully healthy, and played like it, too. Either way, this should be a highly competitive and intriguing game of cat and mouse. Wawrinka is a rhythm player, and during Slams he’s been known to get into an unbeatable one. But Medvedev’s specialty is breaking up his opponent’s rhythm. Judging by his form so far—he’s dropped one set in three matches—he’s doing it just as well he did over the second half of 2019.
 Alexander Zverev vs.  Andrey Rublev
The hair, the ground strokes, the Russian background, the sporadic spasms of rage: When Rublev popped up on the tennis radar screen three or four years ago, he looked like he could have been Zverev’s little tennis brother. In fact, Rublev is just six months younger, and they’ve been friends and rivals since they were 10 years old. In their previous meetings, the (slightly) older brother has been firmly in command: Zverev is 3-0, and has yet to drop a set. If Rublev is ever going to change that dynamic and come out from Zverev’s taller shadow, this would seem to be the time to do it. He’s already won two titles this year, and he’s coming off a gritty four-set win over a higher seed, David Goffin, that didn’t come easily. More important, when Rublev's on, he’s the harder and more decisive ball-striker.
 Rafael Nadal vs.  Nick Kyrgios
A banner day of men’s matches will be capped by this much-anticipated showdown between the sport’s least likely beer-drinking buddies. Not too surprisingly, Kyrgios has traveled a bumpier road to their late-night collision. On Saturday, he let a two-set lead slip against Karen Khachanov, and came within two points of defeat in a fifth-set match tiebreaker, before rallying at the 11th hour. Speaking of tiebreakers, it seems safe to say there will be a couple of them when Kyrgios faces Nadal, and that they will prove decisive.
In 2019, the Spaniard and the Aussie met two times, and they played two breakers in each of those matches. The first time, in Acapulco, Kyrgios raised his level and won both. The second time, at Wimbledon, Kyrgios’ level dropped while Nadal remained steady. If the result is decided by just a few points, who seems more likely to win them? Kyrgios will be buoyed by an arena full of supporters, and by a chance to help his countrymen by winning. Will it be enough to keep him positive if and when things go south? With Nadal, the worry might be his nerves. Openings on Kyrgios’s serve may be few and far between; will he be able to pull the trigger successfully when they present themselves? History says yes. There’s a reason that Kyrgios himself has said this week that Rafa might be the greatest of all time.