MELBOURNE, Australia — one rarely has to wait long for Rafael Nadal, the no. 2 player in the world and the most formidable defender in tennis, to do something amazing. He’ll struggle for a time and give his opponents false hope, as he did in the first set of his Australian open quarterfinal against Jarkko Nieminen, the wiry Finn who beat the man who beat Andy Roddick. Then, suddenly, it happens. Against Nieminen, it was a forehand volley lob that Nadal hit after he had run past the ball and stopped mid-stride. The ball flew over Nieminen’s head and dropped just inside the baseline. Set point for Nadal and for Nieminen, the beginning of the end.

It’s only January, but Rafael Nadal is playing like himself in Melbourne, stalking the baseline, whipping his forehand from corner to corner, and smothering his opponents until they either quit (as Paul-Henri Mathieu did) or wilt in the Melbourne sun (Nieminen and others). Nadal will play in the semifinals Thursday evening in Melbourne, his first semifinal here and his first at a hard court Grand Slam. He’ll be a heavy favorite against Jo-Wilfried Tsonga, a 22-year-old Frenchman whose flashy, attacking tennis, good looks, and charisma have won the hearts of fans at this tournament, if not those of his unfortunate opponents (including Andy Murray and Mikhail Youzhny).

In past years, Nadal did not begin to play his best tennis until March. He has had some decent results here (in the fourth round and quarterfinals) but has never gone this far in a hard-court major without suffering so much as a paper cut. Nadal has played the least tennis of the men who remain in contention for the first major title of the season, as all his matches have ended in three sets except for one. (That match, against Mathieu, ended in fewer than two sets when Mathieu decided he had had enough and retired.) Compare that to last year’s u.S. open, where Nadal was visibly in pain by the time he met David Ferrer in the fourth round. At that tournament, there was a sense early on that Nadal would not have the stamina to survive the rigors of a two-week event. In Melbourne, so far, he has energy to spare, thanks to his strong play and a favorable draw that put him on the opposite side of several men whose powerful strokes give Nadal fits (James Blake, Tomas Berdych, and Fernando Gonzalez, to name a few).

Better still, Nadal’s forehand is in rare form so far. Few people think of Nadal, or baseliners in general, as “feel” players. The adjective is usually reserved for someone like Roger Federer, Murray, or Fabrice Santoro, the 35-year-old Frenchman who slices with two hands on both his forehand and backhand. It’s a mistake to look at Nadal as a ball basher with fast feet, however. His forehand is a complicated stroke: The swing is longer than any coach would desire for a professional, the path of his swing often accentuates upward movement (which imparts spin) rather than outward movement toward the net (for depth and pace), and he routinely hits the ball with his weight on his back foot. Frankly, it’s an awkward shot and surprising not only for its effectiveness but for its consistency. In tennis, simplicity aids repetition; Nadal, somehow, has learned to repeat a decidedly complex shot for hours at a time without making a mistake.

After five matches in Melbourne, Nadal says he is “touching” his forehand “perfect every time.” (Nadal uses the word “touch” instead of “hit” because he speaks imperfect English, but I think the word “touch” is more accurate, considering the spin he puts on the ball and the control he has over it.) For two years now, columnists, coaches, Nadal’s uncle Toni, and Nadal himself have talked about his desire to play closer to the baseline on hard courts and hit his forehand with more depth and pace. There’s no question Nadal has worked on this — one need only look at his results at Wimbledon and in a few other hard court tournaments, like Indian Wells, which he won last year, to find proof. This is the first time, though, that he has hit the ball this well at a major tournament outside of Paris or London. In interviews the last few days, Nadal sounds confident, and a confident Nadal is as dangerous a player as this game has ever known. At the U.S. Open, Nadal defeated Tsonga in straight sets. The first set ended in a tiebreaker; Tsonga won only three games the rest of the way. When they meet on Thursday evening, the first set will be crucial. Tsonga, once the no. 2 junior in the world and a former junior U.S. Open champion, is more imposing than the rugged Nadal (Tsonga stands at 6-feet-2-inches, and weighs 200 pounds, all of it muscle). Tsonga, whose father was a champion handball player for Congo, struggled in his first few years on the tour because of back and knee injuries, but he has been healthy for more than a year now.

In Melbourne, Tsonga’s confidence — and the degree of difficulty of his acrobatic running forehands and lunging volleys — seem to increase every match (he demolished Youzhny in the second set Tuesday evening, winning it at love). If he wins the first set, Nadal will be in for a nasty fight against a hard-serving opponent who will attack the net and won’t give Nadal much time to prepare. If Nadal wins the first set — well, stamina is not Tsonga’s strength, at least not that anyone has seen so far.

Melbourne is often kind to young or unheralded players, as it was to Marcos Baghdatis two years ago. (Remember Thomas Johansson, the 2002 winner, or Rainer Schuettler, the 2003 finalist? Don’t worry, few people do.) If Tsonga is indeed on one of those magical runs, we ought to see a beautiful match.

Mr. Perrotta is a senior editor at Tennis Magazine. He can be reached at tperrotta@tennismagazine.com.