On a day when Jo-Wilfried Tsonga hoped to move one step closer to a rematch with Rafael Nadal in the Australian Open semifinals, the fifth-seeded Frenchman found his path blocked by another Spaniard. Before Nadal even had a chance to avenge last year’s loss to Tsonga, Fernando Verdasco vexed the man who reached the 2008 Australian Open final. The 7-6 (2), 3-6, 6-3, 6-2 victory gave Verdasco his first-ever Grand Slam semifinal appearance, and assured Spain of a finalist in Melbourne.

Just how did Verdasco follow up his rousing five-set win over Andy Murray with another primo performance against the huge-serving Tsonga? Quite simply, the No. 14 seed, who will crack the top 10 before too long, displayed the kind of poise possessed by the greatest players in this sport.

Tennis’s unique scoring system is structured in a way that favors the calm and composed competitor. Tennis matches aren’t won with aggregate accumulations of points; they’re won by the player who can win the most clusters of points.

Tennis doesn’t hand out bonus points to the player who wins the most love games in a set; as long as a player wins a series of four points by a margin of at least two, that player wins a game and thereby establishes an advantage in a set. This advantage exists regardless of the total number of points won.

For example, “Player A”, by winning four games at love, would win 16 more points than an opponent. “Player B”, by winning six games at 30, would win 12 more points than an opponent. If aggregate scoring meant anything in tennis, Player A would defeat Player B in a given set. But under the sport’s existing rules, it’s Player B who would defeat Player A.

The lesson should be clear enough: The most successful tennis players on the planet manage to win the points they have to win. They save break points. They fight off set points. They usually dominate in tiebreaks, and they come through late in a set when the stakes are particularly high.

In Wednesday’s indoor match caused by record-breaking heat in Melbourne, it was Verdasco who won a vast majority of the afternoon’s biggest points.

In the first set, Verdasco used a blended and multifaceted attack to claim a tiebreak–the ultimate big-point showcase–in rather impressive fashion. A combination of huge serves, steady groundstrokes, and above-average defense enabled Verdasco to gain the upper hand despite an utter inability to break Tsonga’s explosive serve.

In the third set, with the match even at one set apiece, Verdasco could only watch as crazy occurrences kept Tsonga in the thick of the fight. Serving at 5-3 and intent on closing out the set, Verdasco saw Tsonga hit a shot between his legs to stay in and eventually save a set point. A short while later, a poor decision by chair umpire Steve Ulrich enabled Tsonga to receive a do-over on a set point that Verdasco had clearly won. Lesser souls would have shriveled in the face of such setbacks, but Verdasco–after taking a little time to gather his swirling emotions–strode back to the service line and officially won the set when a Tsonga backhand sailed long.

By being calm in the face of adversity, Verdasco gained a huge edge against an emotionally volatile opponent. Even more important, Verdasco triumphed over his own mind, which had collapsed in all the Grand Slam tournaments that had preceded this journey to Australia.

Because Verdasco showed such considerable strength in the first and third sets of this immensely entertaining encounter, the Spaniard gave Tsonga reason to doubt his own abilities. The grueling nature of Grand Slam matches makes it hard to come back from a two-sets-to-one deficit. If the stakes are substantial and nerves can’t easily be held in check, the player trailing in a match will feel all the pressure in the world. It was essential for Verdasco to be leading after three sets, and when his steely resolve kicked in on big points at the end of the third set, the most ascendant new figure in the Spanish tennis cosmos had already taken the biggest step toward a career-changing victory.

The fourth set would feel like a foregone conclusion, as an evidently tired Tsonga made a sincere effort to compete, but simply had no juice in his legs. Spent and exhausted, Tsonga suffered mightily in terms of his court coverage and his ability to generate extra velocity on his first serve. Verdasco patiently ran Tsonga around the court, eventually wearing down a player who–with more match play–will become a fitter and more formidable presence on the ATP Tour as 2009 continues.

If a single fact told the story of this match, there’s zero debate about the topic in question: break point conversion rates. Verdasco–becoming the big-point player who is learning how to conquer the crucible of late-round Grand Slam anxiety–converted all four of his break points in this tussle, while an unsettled Tsonga could only convert 2 of 13 break points. The Frenchman’s inability to read Verdasco’s wide-swinging first serve to the ad court resulted in most break point failures, but even when the two men engaged in rallies, it was indeed Verdasco who usually offered the final and most convincing answer. By mastering the moment when break points came calling, Fernando Verdasco improved what had already been the greatest chapter of his tennis-playing life.

A semifinal encounter with Rafael Nadal will be gravy. Tonight in Melbourne, Mr. Verdasco can already rest, safe in the knowledge that his career is finally acquiring the upward trajectory that is consistent with a player of his skill and ability.