Facing the shortcomings that lead to stinging defeats is humbling for any athlete. And yet what separates the champions from the promising is not just honest reflection but the resolve and perseverance to improve those shortcomings, even after setback upon setback.

That has been the story of Andy Murray's career.

While at Wimbledon in 2009 to play in the over-35 doubles (which some call "the seniors," but I'd rather refrain), I slid into a seat on Centre Court to watch Murray take on Andy Roddick in the semifinals. Shouldering the hopes of a nation to end the seven-decade drought of a native man winning Wimbledon, the 22-year-old Scot gamely battled the American to a close four-set loss.

As Roddick pounded serve after serve and forehand after forehand, dictating the outcome of most every point, I remember thinking that Murray — despite his deft movement, crafty counterpunching and minimal unforced errors — did not possess the aggression and weaponry that the modern game necessitated in its Grand Slam champions.

The next day, the Guardian said as much, opining: "Perhaps Murray was a little passive throughout, waiting for Roddick to make mistakes rather than forcing the pace." Exactly.

There was another obvious deficiency, an emotional negativity, that juxtaposed with his tactical passivity. In other words, Murray was overly controlled with his game but lacking it with his mind. Hardly a point was lost by Murray without him showing everyone exactly how disgusted he was. One moment he'd be screaming at himself, the next at his box of family, friends and coaches. John McEnroe may have ranted his way to seven Grand Slam titles, but in this new era being temperamental doesn't seem like a good plan.

More of the same followed the next few years — high-level tour results with some deep forays into majors, including two finals, only to fall disappointingly short. When Murray sobbed on Centre Court after losing to Roger Federer in the final of Wimbledon in 2012, making him 0-4 in major finals, one could feel his pain.

A revolving door of coaches had come and gone during his seven years on tour, all doing their best to steady the porpoising craft. But it was the man who had taken the helm in earlier 2012 who would be the elixir. If opposites can make a marriage, then that explains Ivan Lendl's impact on Andy Murray. In his day of dominance, Lendl was the anti-McEnroe — tireless, expressionless, ruthless. Murray desperately needed some of that.

Lendl imparted stability to Murray's mind and implored more weight to his shots until they finally struck gold, literally. Just three weeks after that bitter Wimbledon defeat, Murray won the Olympics in London, ironically on Centre Court of the All England Club against Federer. The desert had been crossed and a spring had sprung. A first major title at the U.S. Open would come a few weeks later and then the biggest one of all the next summer at Wimbledon.

A split with Lendl in 2014 saw Murray return to his runner-up ways, losing two more major finals to Novak Djokovic (he's lost five in all to the Serb). But the Czech guru was coaxed back in June, just in time to guide Murray to a second Wimbledon title and another Olympic gold in Rio. Add the 2015 Davis Cup title, the first for Britain since 1936, and nobody is talking about Murray's up and down road. He is a future Hall of Famer, earned most deservedly among the great triumvirate of Federer, Djokovic and Rafael Nadal.

With the amount of tennis he has played of late, the 29-year-old Scot is bound to be low on fuel coming into this year's U.S. Open. But he will still be the co-favorite with defending champ and world No. 1 Djokovic. In winning his second major of the year at Roland Garros, Djokovic was on track for a calendar-year Grand Slam. But after a shocking third-round loss at Wimbledon and a first-round exit in Rio, the Serb enters New York with something to prove. Even with last year's finalist and five-time champ Federer out for the year with injury and two-time winner Nadal climbing back from the same, there are a handful of others who can push the top two. That includes 2014 winner Marin Cilic and Rio silver medalist and 2009 champ Juan Martin del Potro.

On the women's side, Serena Williams will be seeking to one better Steffi Graf's 22 majors, leaving only Margaret Court's 24 Grand Slam victories as the final frontier. But don't expect the same degree of scrutiny as her calendar-year Grand Slam quest last year, which ended unimaginably against Italian Roberta Vinci in the semifinals.

Tennis, like life, is a journey. If we learn anything from Murray, it's to keep pressing on, to keep improving, even and especially after disappointments and setbacks. And there is nothing that demands more from a player than the next two weeks in New York at the U.S. Open.

Minnesota's David Wheaton is a former tennis pro whose latest book, "My Boy, Ben," is the story of a special yellow Lab from his playing days. Find out more at davidwheaton.com.