He answered with clarity and conviction when we spoke, only two hours after the first of the year's four big tournaments got underway. "I felt it was time for me to take a break," said Sampras from Los Angeles, where he is spending much of his time these days. "I am doing this for the long run because I want to play this game for many years, into my early and mid-thirties. I see this as the start of being smart with my schedule to stretch my career out."
It was in late December that Sampras realised he was fundamentally in the wrong frame of mind to play the Australian Open. He had thoroughly drained himself in the latter stages of 1998, appearing in six consecutive European indoor tournaments over the autumn, pushing himself unreasonably hard in the process. In the last of those debilitating events, he was unrecognisable during a hard-fought defeat against Jason Stoltenberg in Stockholm.
"After the first set," he recalls "I threw my racket down and cracked it in a million pieces. I was so stressed out from the whole race for No 1, I wasn't eating or sleeping well. I have never done that in my career and I was on the edge. I just snapped for a moment but it felt pretty good to do it."
Sampras went home exhausted, but two weeks later garnered a record-breaking sixth No 1 year-end world ranking in a row on the official ATP computer by reaching the semi-finals in Hanover, Germany.
"After Hanover, I was empty in every aspect, physically, mentally and emotionally," he said. "I had been absolutely consumed with the game through that whole time in Europe and I wanted time to enjoy what I had achieved with the ranking because it was one of the biggest accomplishments of my career. It had become almost a mission to me. I needed to chill out and reflect on what I had done in the game. If the Australian Open had started in February, I would have been ready."
Clearly, Sampras wants to make certain he can recover much of the enthusiasm he felt was missing too often last year. In all his stellar seasons at the top of his profession, Sampras had won at least five tournaments but in 1998 he collected only four. As he points out: "It was probably my worst year of all the years as No 1, but when you win Wimbledon and end the year No 1 you can't complain too much. 1998 wasn't quite as consistent for me as other years. I have created this unbelievably high standard for myself that if I don't win eight or nine tournaments it is a bad year. But this year I am looking for more consistency."
It seems certain that a pivotal moment for Sampras in 1999 will be his return to the lawns of Wimbledon, the place where he has done the most to raise his reputation. By besting Goran Ivanisevic in a compelling five- set final last year on the fabled Centre Court, Sampras tied Bjorn Borg's modern record of five singles championships at the world's most prestigious event. He has a very realistic chance of winning Wimbledon three years in a row for the second time in July.
Seldom if ever has Sampras seemed as genuinely overcome as he was by his triumph over Ivanisevic last July. Even in his post-match press conference, he could barely find the words to translate his emotions. "As a kid growing up," he says now, "I watched Borg play McEnroe in their great matches. I just figured that Borg winning five Wimbledons in a row (1976-80) was one of these things in tennis that no one would ever touch again. So coming through in my first five-set final in a Grand Slam event to win Wimbledon for the fifth time in six years was really overwhelming for me.
"Everybody talks about Borg at Wimbledon and I was kind of put into that class. I always thought Borg's was one of the ultimate achievements in tennis and I matched it. Now I am in a position to break it one day and that really hits me hard."
But will Sampras find a way at last to win the only major championship to elude him? Is this his year at the French Open? "If anything," he says, "I am going to be fresh in Paris this year and that is what I need for the French. I have to go in there and really want this and believe that I can do it. Over the years, the toughest question I have had to answer is why can't I win the French Open? I just have to believe I can do it, and I do believe it. I just need things to fall into place for me there."
As usual, his highest priorities remain the upcoming Grand Slam events. Does that leave room for the Davis Cup, and will Sampras represent the United States in a first- round showdown at Birmingham against the British in April?
"As of right now," he said, "I am not going to play and there are a number of reasons. But what sums it up for me is that when the year is over and I look back there are two things I want to achieve: winning a Grand Slam title and ending the year No 1. I feel Davis Cup puts both of those goals in jeopardy. I understandably get a bad rap for this. I really want to play but at what point do you sacrifice your ranking or the Grand Slams for Davis Cup?"
Sampras recognises that if he and Andre Agassi do not face the British at Birmingham, the United States will almost surely fall against Tim Henman, Greg Rusedski and company. Does he believe Henman and Rusedski could take their nation all the way and what does he expect from both of these formidable competitors individually?
"The British have a good chance depending on the draw. On the right surfaces they have as good a chance as anybody to win it. Individually, this could be a breakthrough year for Henman, who wants to take that next step and win a major. He is on the verge of doing it, and the same can be said for Rusedski."
While the absence of Sampras and the withdrawals of Marcelo Rios and Ivanisevic were significant news items, the major story at the outset of the Australian Open surrounded the defending champion, Petr Korda. After testing positive in a drug test taken at Wimbledon last year, Korda claimed he had no clue how the steroid nandrolone got in his system.
Korda would have been suspended for one year, but an appeals committee of the International Tennis Federation voted to remove that punishment and Korda merely lost his Wimbledon ranking points and prize money.
The ITF is considering overturning its own appeals committee - but they may be stopped by Korda's lawyers.
Sampras addresses this thorny issue candidly and intelligently. Along with many of his fellow players, he is deeply disturbed by the Korda controversy and its implications.
"When I heard about Petr, I was very surprised," Sampras said. "I know him pretty well and he would be the last person that would use a steroid or cheat. I guess he was unaware of what he was taking, but to me you can't plead ignorance.
"The reason we have these drug tests is to make sure the game is fair, so as a competitor it bothers me that he has been allowed to play in Australia."
But while he is perplexed by Korda's seemingly lame excuse, Sampras is baffled as well by the way this has been handled by the authorities.
"Why are we doing random drug tests 10 times a year at tournaments if we are not going to uphold the rules?" he said. "It makes the game look bad. Petr is trying to clear his name, which I can understand, but rules are rules."
Be that as it may, Sampras is too much of a professional to be distracted by the trials and tribulations of other competitors. He is firmly immersed in his own objectives. He recently returned from a one-week vacation in Hawaii with his girlfriend, Kimberly Williams, an accomplished actress. Last week he appeared in the Bob Hope Golf classic in La Quinta, California, playing in the pro-am division.
On 8 February, though, he will return to the ATP Tour in San Jose, California, after 10 weeks away. From that moment on, it will be back to the business of his trade.
Sampras expects to sense the full impact of his decision not to compete in the Australian Open as the tournament progresses.
"When I see who is still in the tournament for the quarter-finals and semi-finals, that is when I will feel it," he said. "I will miss the chance to hold up that cup again. I am going to hate it not being there, but I know this is the best thing for me to do. I guess I look at this as coming back for my second career after a big life decision."