David Wheaton previews the Australian Open

As Minnesotans were reminded last Sunday, nothing is a sure thing in sport … not even a 27-yard field goal.

Tennis fans need only rewind to September and the women's semifinals of the U.S. Open for our sport's version of the missed chip shot, when Serena Williams, poised to win a rarer-than-air calendar-year Grand Slam, inconceivably stumbled to an unseeded player from Italy. Picking the correct five Powerball numbers seemed like better odds than predicting that result.

Which leads to another sport truism: Things change in a hurry. Even with her shocking defeat in New York, Williams had an amazing year, tallying a 53-3 match record, raising her major championship total by three to 21, and garnering Sportsperson of the Year honors from Sports Illustrated.

And so naturally the player that everyone is talking about coming into the Australian Open is … Novak Djokovic.

While Serena shut down her engines for the rest of the year after the U.S. Open, men's winner Djokovic revved things up, winning all four tournaments he played, including the year-end World Tour Finals. The latter was the icing on his own incredible year, one that included an 82-6 match record and 11 titles, three of them majors. If not for Swiss striker Stan Wawrinka hitting him off the court in the French Open final, Djokovic would have his own calendar-year Grand Slam.

Djokovic started 2016 by winning in Doha, thumping Rafa Nadal 6-1, 6-2 in the final. So superior is Djokovic right now that Nadal could only effuse, ''I know nobody playing tennis like this ever. … When I say perfect, it's not one thing in particular. It's everything."

This from a peer who we all thought was half of the two-man race for Greatest Ever. The other half being the original Mr. Perfect, Roger Federer. After all, Nadal has 14 majors and Federer the record 17. No one's catching them for decades, right? Let alone Djokovic, who has 10.

Technically, the strength of Djokovic's game is that he without weakness. He may not possess the fearsome forehand of Federer or the once-booming serve of his coach, Boris Becker, but each of his strokes is so sound that the rare unforced error elicits surprise. His return of serve and two-handed backhand are without doubt the best of his generation … and maybe all generations.

And yet what allows for Djokovic's technical solidity is his physicality. Where Nadal bludgeons with strength and sinew, Novak floats and stings with an unsurpassed blend of agility, balance and flexibility. His movement is so deft, his footwork so precise, it leads to his remarkable stroke reproducibility and deadly accuracy down range. When on defense, his gymnast-like ability to do the splits on full stretch saves many a point.

His physical attributes are more nurture than nature, by the way. Djokovic is renowned for his attention to his flexibility regimen, his oxygen and hydration levels, his gluten-free diet, and, well, you get the picture. If his razor-thin frame looks like it's not carrying an extra ounce of fat, that's because it's not and he won't let it.

The Serb's lock-tight mentality completes the package. Compared to his main rivals, he's more warrior than Federer, more confident than Nadal, and more settled than Andy Murray. The story goes that at 12 in Belgrade he had to alternate between practicing tennis in an empty swimming pool and retreating to the bomb shelter to avoid NATO air raids. One doesn't need to wonder where he gets his tenacity.

Melbourne has been one of Djokovic's most prolific stops on tour. If not for that pesky Wawrinka playing in the zone (again) in the 2014 final, Novak would be gunning for six in a row. Instead he's simply the defending champion and heavy favorite. The first major always bring some extra surprises and the Australian summer heat can make even the fittest wilt.

Minnesotan David Wheaton missed his share of gimmes on tour, but he did reach the quarterfinals of singles and the finals of doubles at the Australian Open in 1990. His latest book, "My Boy, Ben," is a true story about a yellow Lab that he had during his pro tennis days. Find out more at davidwheaton.com.