Federer-Nadal Rivalry Adds Another Chapter MELBOURNE, Australia - The rivalry between Rafael Nadal and Roger Federer is now a fully formed, fully explored phenomenon, one that has put them on a first-name basis with much of the planet. They meet for the 27th time on Thursday (3:30 a.m. Eastern, ESPN2), in the semifinals of the Australian Open. It has required a remarkable series of circumstances for Roger and Rafa, two Europeans from comfortable backgrounds to evolve into a yin-and-yang for the ages. What were the odds that two players of their dimensions and drive would both emerge in the same era from the same time zone? What were the odds that, in a sport pocked by injuries, they would endure long enough to build that kind of narrative momentum? What were the odds, despite the language barrier and their conflicting aims, they would make their rivalry into something so gripping despite the lack of a rough edge? They have lifted and defined each other without disliking each other and perhaps that is because both are savvy enough to realize that neither would have made it this far without the other to motivate them through workaday training sessions and early-round matches in minor tournaments. Without Federer as his measuring stick, Nadal might not have remained so focused on becoming a complete player. Without Nadal as a reminder of his limitations, Federer might have become complacent by age 30 instead of remaining hungry for more titles, more travels, more athletic challenges, even with twin daughters in tow. What comes through in both men is a deep respect for the process, for the game itself, even if there have been signs of estrangement of late with disagreements between them over tour politics. The differences of opinion are real, and Nadal even criticized Federer sharply in a pre-tournament news conference here for not speaking out and for letting other players take the flak. But Nadal, who leads their series by 17-9 and has a 7-2 edge in Grand Slam play, said the next day he regretted not speaking to Federer in private, and Federer said there was no extra edge to this match because of Nadal's comments. "Honestly, no," he said. It was here for one day and then gone again. I'm happy about that, because it didn't deserve more attention than it did. But that does not mean there will be no added meaning to their 27th meeting. Their rivalry have been memorable from the start, with Nadal, then just 17, stunning Federer on a hardcourt in Miami in 2004 by winning 6-3, 6-3. Well-warned the second time when they faced each other in the same city in the final, Federer needed five sets to escape. They have been answering questions about each other, with fluctuating degrees of patience and emotion ever since. But Federer has had to answer the tougher ones. Nadal has reduced him to tears on at least two occasions, after ending his five-year run at Wimbledon in the 2008 final and, even more poignantly, after beating him for the fifth time in a row in the 2009 Australian Open final. "God, it's killing me," Federer muttered as he lost his composure during the ceremony, with Nadal offering him a shoulder for support. They have played seven times since then, with Nadal winning four and Federer three. They played four times last year, with Nadal winning in the semifinals in Miami and Madrid and in the final of the French Open. But Federer stopped the streak emphatically when he dismantled Nadal, 6-3, 6-0, in the round-robin phase of the ATP World Tour Finals in November. Federer, not Nadal, has been on the much bigger roll of late. He has not lost since the semifinals of last year's United States Open, winning his last 24 matches. His only blemish came when he retired before the semifinals in Doha with his back problems. In Melbourne, he has yet to drop a set, but Nadal is, as ever and perhaps even more at the Australian Open, a rival apart. "Even if it's not a final, it's still a huge match," Federer said.