There are certain moments that happen in sports that you know will change the way things are viewed from there on out: the Red Sox coming back from an 0-3 deficit to beat the Yankees and then go on to win their first World Series in 86 years, Buster Douglas knocking out Mike Tyson to become the heavyweight champion, and NC State taking down Houston to win the NCAA Tournament to name a few. Sunday’s final round of the PGA Championship is now one of those moments.

After last year’s U.S. Open, I wrote that Tiger Woods’ putt on the 72^nd hole to force a playoff was amazing for so many reasons, but maybe none more so than the fact that it kept his invincibility in tact. Think about it for a minute, had Tiger missed that putt, he would’ve lost to 45-year old Rocco Mediate (a man who had never won a major), after entering Sunday’s final round with the lead. It would’ve marked the first time in his career that he failed to win a major after taking the lead into Sunday.

Now you may say, big deal, so what. But it is a big deal, and the reason why is because had Tiger lost, it would’ve given other players, players much better than Mediate, the confidence to know that Tiger is, in fact, beatable. Instead, Tiger added to his legacy by sinking that putt, and then doing it again the very next day.

Fast-forward to Sunday’s final round at the PGA Championship, and we were once again faced with the same scenario. Although this time Tiger’s opponent was someone much more obscure than Mediate, it was Y.E. Yang from South Korea. Besides the point that barely anyone knew who Yang was, the fact that Tiger had the lead entering Sunday meant everyone KNEW he was going to win. After all, he was a perfect 14-for-14 when leading after 54 holes of a major. So in other words, the final 18 was all but a formality before handing Woods his fifth Wanamaker Trophy.

But somehow, some way, Yang was able to do what nobody else in the last 12 years has been able to do, and that’s go head-to-head with Tiger in the final round of a major and beat him. So what does this all mean? Well, it certainly opens up a bunch of possibilities.

If you look at the examples from above, the one most similar to this is Buster Douglas knocking out Mike Tyson. Tyson was the most feared man alive. Professional boxers, men who got PAID to do this, would literally shake in the ring at the near sight of Tyson. Along comes Douglas, who yes was a contender, but no one thought a legitimate one, and he knocks out Tyson. What did Tyson do after that fight with his career? Nothing really.

Now I’m not saying this is going to happen to Tiger by any means, but I do believe other golfers will gain confidence in knowing that he’s no longer invincible, and those final rounds of majors will suddenly become that much more interesting.

The mark of a true champion is measured by how they deal with adversity, and there’s no greater adversity in sports than losing. Michael Jordan lost in the 1995 playoffs to the Orlando Magic, and he came back to win three straight titles from 1996-1998. Roger Federer lost to Rafael Nadal in the finals of Wimbledon in 2008, and came back to win another epic match against Andy Roddick this year to break Pete Sampras’ mark of 14 grand slam titles. Tiger Woods now gets to deal with this type of adversity for the first time in his incredible career. Either way he responds, you will be able to look back at August 16, 2009, and know that history was made.