After his first Masters victory in 1997, it was hard to imagine that anybody could ever contend with Tiger Woods on the Augusta National course. Not only was he the youngest winner, at 21 years and several months, but he shot the lowest 72-hole score in the tournament's history, an 18-under-par 270, and won by the largest margin ever, 12 strokes.

But in the dozen seasons since Tiger walked off the course with his first major title, it has never again proved to be quite that easy. Still, Tiger has captured three more green jackets—by two strokes over David Duval in 2001, by three over Retief Goosen in 2002 and in a playoff with Chris DiMarco in 2005—along with three U.S. Open championships, three British Open crowns and four PGA Championship titles.

As he tees off at the Masters on Thursday at 1:52 p.m. ET, once again as the prohibitive favorite, it remains an article of faith that Woods is the greatest the game has ever seen and that he will one day surpass Jack Nicklaus's career mark of 18 major championships. But just like that original projection for the Masters, this one may not prove to be so easy either.

So while you watch the numbers on Tiger's scorecard, there are other numbers to consider too: 33, 5, 4 and 2.

The first is, of course, Tiger's age, 33 and still at the top of his game. Tiger is such an exceptional talent and maintains such superb conditioning that he may defy all the conventional wisdom about age and golf. But there tends to be a limited window in which even the greatest players can compete. In the 75-year history of the Masters, only five champions, had already celebrated their 40th birthday: Ben Hogan at 40, Sam Snead and Gary Player both at 42, Mark O'Meara at 43 and Nicklaus at 46. Arnold Palmer, who with four career Masters victories shares second place with Woods behind Nicklaus's six, won his last at age 34.

The number five represents the number of major titles Woods needs to surpass Nicklaus. That may not seem like all that many, especially given that Tiger has won six majors over the last four years. But before that streak, Woods endured a two-year slump without a single major win. Since his first Masters win, Tiger has captured, on average, a little more than one major tourney a season. At that pace, he will require slightly more than four seasons—perhaps the 2013 Masters will be the place—to surpass Nicklaus's record. The human obstacles are many. Beyond the usual suspects standing in Woods's path, like Padraig Harrington who, absent Tiger, has won the last two majors, and Phil Mickelson, who appears back in form after a pair of early-season victories, there is remarkable depth in today's golfing ranks.

Moreover, new talent is coming up faster than ever, or at least more of it is. Only 23 teenagers, including Woods, Nicklaus, Seve Ballesteros and Sergio Garcia, have ever played the Masters. This year, three teens will be making their debut: Northern Ireland's Rory McIlroy, who at 19 is already ranked 17th in the world; South Korea's Danny Lee, 18, who last year became the youngest player ever to win the U.S. Amateur, eclipsing Tiger's record by seven months; and Japan's Ryo Ishikawa, 17, who became the youngest player ever to win on a major pro tour when he captured a tournament in Japan at age 15.

The number four represents the number of knee surgeries Tiger had now endured. In his stirring 2009 U.S. Open victory, Woods demonstrated that he could play on one leg and still beat all comers. And in his win last month at the Arnold Palmer Invitational—a double comeback in that he came from behind while playing in only his second tournament since his nine-month hiatus to recover from the knee surgery—Tiger demonstrated that he is back in command. Still, the combination of age and injury is the most serious threat to ongoing success in all sports.

Finally, the number two represents the number of children in the Woods family. Tiger's daughter, Sam Alexis, will be 2 in June and his son, Charlie Axel, is barely 3 months old. Woods's recovery from knee surgery came with a hidden blessing, a chance to spend extensive time with his children. Given how Tiger honors the example of his own father, we can assume he intends to be more of an involved dad than an absentee one. As his children grow older, there will inevitably be some tug between his golfing ambitions and his parental responsibilities. Fulfilling the later can certainly constrain the former.

Most fans still believe that Woods will attain that record for career majors. But life is fickle and, among its games, golf is as fickle as any. Even his fans recognize that and insist that the record ultimately doesn't matter, that Tiger is clearly the greatest player ever.

We tend to dismiss athletes from the past, many of whom fans with strong opinions never even saw, and easily bestow that "greatest ever" level on our contemporaries: Michael Jordan rather than Oscar Robertson; Roger Federer rather than Rod Laver; Muhammad Ali rather than Joe Louis. I happen to believe that when it comes to our final judgment on Tiger, it does matter whether he captures the record. Indeed when it is the extraordinary career of "The Golden Bear" at issue, it matters a great deal.