The jockey who came from behind and rode Union Rag to the Belmont crown today, believed his horse could win it, despite its failure to win in the past.

So did its owner, a woman who had sold Union Rag, then relented and bought the horse back for three times the cost.

Maria Sharapova never came close to winning the French, much less getting to the final, but worked very hard on her game after a long run of sidelining injuries, and believed she could do it – e.g., regain the #1 ranking and win the Grand Slam of Tennis, joining only six other women who have ever won all the slams.

And Djokovic, down four match points in the French Open quarter-finals last week, after going down two sets, simply believed he could pull it out, and did (stay tuned for his final against Nadal tomorrow).

Tiger Woods, who hadn’t won a tournament in a long while, and with many tennis fans counting him down and out, believed he could win the Jack Nicklaus Memorial Tournament last Sunday, and did.

And the Miami Heat just now won the NBA Eastern Division title, beating the Boston Celtics in Game 5, 100-88. LeBron James scored 30+ points and said, in the post-game interview: “We believed.”

Seems to me that belief matters a great deal, and that these heroic triumphs prove it.

Having positive expectations that you can win is a hallmark of champions. In all of the examples above, they believed it was possible to win so they trained for it. Belief runs deep. It is the feeling that you have the skills to perform well when the stakes are high. It is not a passing feeling. You expect to win if you play well.

Before my last world championship win in February, 2012 playing the #1 ITF player in the world, I believed and expected to win, but it ended there. Then, it was all about preparing myself for the moment–doing the right things to feel good. I never said to myself or another that I “should” beat him (what I now consider to be a swear word in sports). But, I did the work, played well and won because I believed.

However, many athletes tell me that they “should” win a tournament or beat a particular team or opponent based on a ranking or past result. In youth sports, this superficial expectation based on outcome is not the same as belief. This is an “outcome-based expectancy,” which is different. It has elements of entitlement, hope, but not necessarily the glue that has them spend an extra 30 minutes practicing serves or doing more crunches for their core.

But, when the best athletes in the world are on their game they have an unshakable belief and expectation that they will get the job done. They want the game or match on the line. They want that pressure. They want it because they believe in the work they put in and they are committed to executing their skills. Make no mistake about it–Nadal, Sharapova, LeBron, Woods–their belief started many years ago and is built upon every single day, pushing themselves to the limit because they believe.